:Imperial units
{{Short description|System of measurements}}
{{About|the post-1824 measures used in the British Empire and countries in the British sphere of influence|the units used in England before 1824|English units|the system of weight|Avoirdupois|United States customary units|United States customary units|an overview of UK and US units|Imperial and US customary measurement systems|the political ideology|Imperialism}}
{{Use dmy dates|date=November 2020}}
File:Weights and Measures office.jpg (590 Seven Sisters Road)]]
The imperial system of units, imperial system or imperial units (also known as British Imperial{{cite book|author=Britannica Educational Publishing|title=The Britannica Guide to Numbers and Measurement|url=https://books.google.com/books?id=cuN7rH6RzikC&pg=PA241|year=2010|publisher=The Rosen Publishing Group|isbn=978-1-61530-218-5|page=241|access-date=1 July 2015|archive-date=14 January 2023|archive-url=https://web.archive.org/web/20230114131616/https://books.google.com/books?id=cuN7rH6RzikC&pg=PA241|url-status=live}} or Exchequer Standards of 1826) is the system of units first defined in the British Weights and Measures Act 1824 and continued to be developed through a series of Weights and Measures Acts and amendments.
The imperial system developed from earlier English units as did the related but differing system of customary units of the United States. The imperial units replaced the Winchester Standards, which were in effect from 1588 to 1825.{{cite book|author=Chaney, Henry James|title=A Practical Treatise on the Standard Weights and Measures in Use in the British Empire with some account of the metric system|url=https://archive.org/details/ourweightsandme00changoog|access-date=11 September 2016|date=1897|publisher=Eyre and Spottiswoode|page=[https://archive.org/details/ourweightsandme00changoog/page/n11 3]}} The system came into official use across the British Empire in 1826.
By the late 20th century, most nations of the former empire had officially adopted the metric system as their main system of measurement, but imperial units are still used alongside metric units in the United Kingdom and in some other parts of the former empire, notably Canada.
The modern UK legislation defining the imperial system of units is given in the Weights and Measures Act 1985 (as amended).{{Cite web|url=http://www.legislation.gov.uk/ukpga/1985/72|title=Weights and Measures Act 1985|website=legislation.gov.uk|access-date=2020-01-20|archive-date=2 January 2022|archive-url=https://web.archive.org/web/20220102140420/https://www.legislation.gov.uk/ukpga/1985/72|url-status=live}}
Implementation
The Weights and Measures Act 1824 was initially scheduled to go into effect on 1 May 1825.{{cite book|author=Great Britain|title=The statutes of the United Kingdom of Great Britain and Ireland (1807-1865)|url=https://archive.org/details/statutesunitedk02britgoog|access-date=31 December 2011|year=1824|publisher=His Majesty's statute and law printers|pages=[https://archive.org/details/statutesunitedk02britgoog/page/n373 339]–354}} The Weights and Measures Act 1825 pushed back the date to 1 January 1826.{{cite book|author1=Great Britain|author2=William David Evans|author-link2=William David Evans|author3=Anthony Hammond|author4=Thomas Colpitts Granger|title=A collection of statutes connected with the general administration of the law: arranged according to the order of subjects|url=https://archive.org/details/acollectionstat08evangoog|access-date=31 December 2011|year=1836|publisher=W. H. Bond|pages=[https://archive.org/details/acollectionstat08evangoog/page/n397 306]–27}} The 1824 act allowed the continued use of pre-imperial units provided that they were customary, widely known, and clearly marked with imperial equivalents.
=Apothecaries' units=
File:Imperial standards of length 1876 Trafalgar Square.jpg, London]]
Apothecaries' units are not mentioned in the acts of 1824 and 1825. At the time, apothecaries' weights and measures were regulated "in England, Wales, and Berwick-upon-Tweed" by the London College of Physicians, and in Ireland by the Dublin College of Physicians. In Scotland, apothecaries' units were unofficially regulated by the Edinburgh College of Physicians. The three colleges published, at infrequent intervals, pharmacopoeias, the London and Dublin editions having the force of law.{{cite book|title=Edinburgh medical and surgical journal|url=https://books.google.com/books?id=DwUbAQAAMAAJ&pg=PA398|year=1824|publisher=A. and C. Black|page=398}}{{cite book|author1=Ireland|last2=Butler|first2=James Goddard|last3=Ball|first3=William (barrister.)|title=The Statutes at Large, Passed in the Parliaments Held in Ireland: From the twenty-third year of George the Second, A.D. 1749, to the first year of George the Third, A.D. 1761 inclusive|url=https://books.google.com/books?id=iIdRAAAAYAAJ&pg=PA852|year=1765|publisher=Boulter Grierson|page=852}}
Imperial apothecaries' measures, based on the imperial pint of 20 fluid ounces, were introduced by the publication of the London Pharmacopoeia of 1836,{{cite book|last=Gray|first=Samuel Frederick|author-link=Samuel Frederick Gray|title=A supplement to the Pharmacopœia and treatise on pharmacology in general: including not only the drugs and preparations used by practitioners of medicine, but also most of those employed in the chemical arts : together with a collection of the most useful medical formulæ ...|url=https://archive.org/details/supplementtophar00grayuoft|access-date=29 July 2012|year=1836|publisher=Longman, Rees, Orme, Brown, Green, and Longman|page=[https://archive.org/details/supplementtophar00grayuoft/page/516 516]}}{{cite web|url=https://archive.org/stream/atranslationpha01philgoog#page/n19/mode/2up|title=A Translation of the Pharmacopoeia of the Royal College of Physicians of London, 1836.: With ...|publisher=S. Highley, 32, Fleet Street.|year=1837}} the Edinburgh Pharmacopoeia of 1839,{{cite book|title=The Pharmacopoeia of the Royal College of Physicians of Edinburgh|url=https://books.google.com/books?id=sTjY2_xKm9UC&pg=PR13|year=1839|publisher=Adam and Charles Black and Bell and Bradfute|pages=xiii–xiv}} and the Dublin Pharmacopoeia of 1850.{{cite book|author1=Royal College of Physicians of Dublin|author2=Royal College of Physicians of Ireland|author-link2=Royal College of Physicians of Ireland|title=The pharmacopœia of the King and queen's college of physicians in Ireland|url=https://archive.org/details/pharmacopiaking00dublgoog|access-date=29 July 2012|year=1850|publisher=Hodges and Smith|page=xxii}} The Medical Act 1858 transferred to the Crown the right to publish the official pharmacopoeia and to regulate apothecaries' weights and measures.{{cite book|author=Great Britain|title=A collection of the public general statutes passed in the ... year of the reign of ...|url=https://books.google.com/books?id=rkovAAAAIAAJ&pg=PA306|year=1858|publisher=Printed by G. W. Eyre and W. Spottiswoode, Printers to the Queen|page=306}}
Units
=Length=
Metric equivalents in this article usually assume the latest official definition. Before this date, the most precise measurement of the imperial Standard Yard was {{val|0.914398415}} metres.Sears et al. 1928. Phil Trans A, 227:281.
| class="wikitable" style="margin-right:0"
|+ Table of length equivalent units ! Unit ! Abbr. or symbols ! Relative to previous ! Feet ! Metres ! Notes |
| twip
| | |align=right | {{frac|17280}} |align=right | {{val|0.00001763|end={{overline|8}}}} |typographic measure |
|---|
| thou
|th |1.44 twip |align=right| {{frac|{{val|12000}}}} |align=right| {{val|0.0000254}} | Abbreviation of "thousandth of an inch". Also known as mil.Jerrard and McNeill, Dictionary of Scientific Units, second edition, Chapman and Hall; cites first appearance in print in Journal of the Institution of Electrical Engineers (G.B.) vol. 1, page 246 (1872). |
| barleycorn
| | {{nowrap|{{Fraction|333|1|3}} th}} |align="right" | {{frac|36}} |align="right" | {{val|0.0084|end={{overline|6}}}} | {{nowrap|{{Fraction|1|3}} in}} |
| inch
|in (″) | {{val|3|u=Bc}} | align="right" | {{frac|12}} | align="right" | {{val|0.0254}} | 1 metre ≡ 39 {{frac|47|127}} inches |
| hand
|hh | {{val|4|u=inch}} |align="right" | {{frac|3}} |align="right" | {{val|0.1016}} | Used to measure the height of horses |
| foot
|ft (′) | {{val|3|u=hand}} |align=right | 1 |align=right | {{val|0.3048}} |12 in |
| yard
|yd | {{val|3|u=foot}} |align=right| 3 |align=right| {{val|0.9144}} | Defined as exactly {{val|0.9144|u=metres}} by the international yard and pound agreement of 1959 |
| chain
|ch | {{val|22|u=yard}} |align=right | 66 |align=right | {{val|20.1168}} | {{val|100|u=links}}, {{val|4|u=rods}}, or {{frac|10}} of a furlong. The distance between the two wickets on a cricket pitch. |
| furlong
|fur | {{val|10|u=chain}} |align=right| {{val|660}} |align=right| {{val|201.168}} | {{val|220|u=yards}} |
| mile
|mi | {{val|8|u=furlong}} |align=right | {{val|5280}} |align=right | {{val|1609.344}} | {{val|1760|u=yards}} or {{val|80|u=chain}} |
| league
|lea | {{val|3|u=mile}} |align=right | {{val|15840}} |align=right | {{val|4828.032}} | |
| colspan="6" style="text-align:center;" | Maritime units |
| valign=top
|ftm | {{val|2.02667|u=yard}} |align=right | {{val|6.0761}} |align=right | {{val|1.852}} | The British Admiralty in practice used a fathom of {{val|6|u=foot}}. This was despite its being {{frac|1000}} of a nautical mile (i.e. {{val|6.08|u=foot}}) until the adoption of the international nautical mile.The exact figure was {{val|6.08|u=foot}}, but {{val|6|u=foot}} was in use in practice. The commonly accepted definition of a fathom was always 6 feet. The conflict was inconsequential, as Admiralty nautical charts designated depths shallower than {{val|5|u=fathom}} in feet on older imperial charts. Today, all charts worldwide are metric, except for USA Hydrographic Office charts, which use feet for all depth ranges. |
| valign=top
| | {{val|100|u=fathom}} |align=right | {{val|607.61}} |align=right | {{val|185.2}} | One tenth of a nautical mile. Equal to {{val|100|u=fathom}} under the strict definition. |
| valign=top
|nmi | {{val|10|u=cables}} |align=right | {{val|6076.1}} |align=right | {{val|1852}} | Used for measuring distances at sea (and also in aviation) and approximately equal to one arc minute of a great circle. Until the adoption of the international definition of {{val|1852|u=metre}} in 1970, the British nautical (Admiralty) mile was defined as {{val|6080|u=foot}}.The nautical mile was not readily expressible in terms of any of the intermediate units, because it was derived from the circumference of the Earth (like the original metre). |
| colspan="6" style="text-align:center;" | Gunter's survey units (17th century onwards) |
| link
| | {{val|7.92|u=inch}} |align=right | {{frac|66|100}} |align=right | {{val|0.201168}} | {{frac|100}} of a chain and {{frac|{{val|1000}}}} of a furlong |
| rod
| | {{val|25|u=links}} |align=right | {{frac|66|4}} |align=right | {{val|5.0292}} | The rod is also called pole or perch and is equal to {{nowrap|{{frac|5|1|2}} yards}} |
=Area=
| class="wikitable" style="margin-right:0"
|+ Table of area units and equivalents ! Unit !Abbr. or symbol !Relative to previous ! Relation to units of length ! Square feet ! Square yards ! Acres ! Square metres ! Hectares |
| perch*
| | |{{val|1|u=rod}} × {{val|1|u=rod}} |align=right| {{frac|272|1|4}} |align=right| {{frac|30|1|4}} |align=right| {{frac|160}} |align=right| {{val|25.29285264}} |align=right| {{val|0.002529285264}} |
|---|
| rood
| | {{val|40|u=perch}} |align=right| {{val|10890}} |align=right|{{Val|1210}} |align=right| {{frac|4}} |align=right| {{val|1011.7141056}} |align=right| {{val|0.10117141056}} |
| acre
| | {{val|4|u=rood}} | {{val|1|u=furlong}} × {{val|1|u=chain}} | align=right| {{val|43560}} |align=right|{{Val|4840}} |align=right| {{val|1}} |align=right| {{val|4046.8564224}} |align=right| {{val|0.40468564224}} |
| square mile
|sq mi |{{val|640|u=acre}} |{{val|1|u=mile}} × {{val|1|u=mile}} |align=right|{{Val|27878400}} |align=right|{{Val|3097600}} |align=right|640 |{{Val|2589988.110336}} |{{Val|258.9988110336}} |
| colspan="9" |Note: *The square rod has been called a pole or perch or, more properly, square pole or square perch for centuries. |
= Volume =
File:Volume_measurements_from_The_New_Student's_Reference_Work.svg
The Weights and Measures Act 1824 invalidated the various different gallons in use in the British Empire, declaring them to be replaced by the statute gallon (which became known as the imperial gallon), a unit close in volume to the ale gallon. The 1824 act defined as the volume of a gallon to be that of {{convert|10|lb|kg|2}} of distilled water weighed in air with brass weights with the barometer standing at {{convert|30|inHg|0|lk=in}} at a temperature of {{convert|62|°F|°C|0|lk=in}}.{{cite web | url = http://www.legislation.gov.uk/ukpga/1824/74/pdfs/ukpga_18240074_en.pdf | title = An Act for ascertaining and establishing Uniformity of Weights and Measures (17 June 1824) | website = legislation.gov.uk | date = 17 June 1824 | access-date = 19 January 2020 | page = 639,640 | quote = Two such Gallons shall be a Peck, and Eight such Gallons shall be a Bushel, and Eight such Bushels a Quarter of Corn or other dry Goods, not measured by Heaped Measure. | archive-date = 20 July 2020 | archive-url = https://web.archive.org/web/20200720182949/https://www.legislation.gov.uk/ukpga/1824/74/pdfs/ukpga_18240074_en.pdf | url-status = live }}. (The date of coming into effect was 1 May 1825). The 1824 act went on to give this volume as {{convert|277.274|cuin|L|abbr=off|sigfig=6}}. The Weights and Measures Act 1963 refined this definition to be the volume of 10 pounds of distilled water of density {{val|0.998859|u=g/mL}} weighed in air of density {{val|0.001217|u=g/mL}} against weights of density {{val|8.136|u=g/mL}}, which works out to {{val|4.546092|u=L}}.10 pounds = 4535.9237 grams. @ 0.998859 g/mL => 4546.092 mL The Weights and Measures Act 1985 defined a gallon to be exactly {{val|4.54609|u=L}} (approximately {{val|277.4194|u=cuin}}).{{cite encyclopedia |title=imperial gallon |publisher=Sizes.com |url=http://www.sizes.com/units/gallon_imperial.htm |access-date=2019-07-10 |date=25 October 2013 |archive-url=https://web.archive.org/web/20110514101804/http://www.sizes.com/units/gallon_imperial.htm |archive-date=14 May 2011 |url-status=live}}
| class="wikitable"
|+ Table of equivalences ! Unit ! Imperial ! Imperial ! Millilitres ! Cubic inches ! US ounces ! US pints |
| align=center| fluid ounce (fl oz)
|align=right| 1 |align=right| {{frac|20}} | {{convert|28.4130625|mL|cuin USoz USpt|disp=table|sigfig=5|comma=gaps}} |
| align=center| gill (gi)
|align=right| 5 |align=right| {{frac|4}} | {{convert|142.0653125|mL|cuin USoz USpt|disp=table|sigfig=5|comma=gaps}} |
| align=center| pint (pt)
|align=right| 20 |align=right| 1 | {{convert|568.26125|mL|cuin USoz USpt|disp=table|sigfig=5|comma=gaps}} |
| align=center| quart (qt)
|align=right| 40 |align=right| 2 | {{convert|1136.5225|mL|cuin USoz USpt|disp=table|sigfig=5|comma=gaps}} |
| align=center| gallon (gal)
|align=right| 160 |align=right| 8 | {{convert|4546.09|mL|cuin USoz USpt|disp=table|sigfig=5|comma=gaps}} |
| colspan=7|Note: The millilitre equivalences are exact, but cubic-inch and US measures are correct to 5 significant figures. |
| class="wikitable" style="margin-right:0"
|+ Unit measures defined by the Weights and Measures Act 1824, ! Liquid ! Dry ! Capacity | ||
| {{1/2}} gill | {{convert|4.32|cuin|mL|abbr=on}} | |
| gill | {{1/4}} pint | {{convert|8.64|cuin|mL|abbr=on}} |
| {{1/2}} pint | {{1/2}} pint | {{convert|17.38|cuin|mL|abbr=on}} |
| pint | pint | {{convert|34.76|cuin|mL l|abbr=on}} |
| quart | quart | {{convert|69.32|cuin|L|abbr=on}} |
| {{1/2}} gallon | {{1/4}} peck or {{1/2}} gallon | {{convert|138.64|cuin|L|abbr=on}} |
| gallon | {{1/2}} peck or gallon | {{convert|277.274|cuin|L|abbr=on}} |
| 2 gallons (peck) | peck | {{convert|554.548|cuin|L|abbr=on}} |
| 4 gallons ({{1/2}} bushel) | {{1/2}} bushel | {{convert|1109.096|cuin|L|abbr=on}} |
| 8 gallons | bushel | {{convert|2218.192|cuin|L|abbr=on}} |
| 64 gallons | quarter | {{convert|17745.536|cuin|L|abbr=on}} |
| colspan=3|Note: The 1824 Act removed the distinction between liquid and dry measure, specifying instead that the dry quantities shall be unheaped. The metric equivalences shown are approximate. |
==British apothecaries' volume measures==
These measurements were in use from 1826, when the new imperial gallon was defined. For pharmaceutical purposes, they were replaced by the metric system in the United Kingdom on 1 January 1971.{{cite web|url=http://www.legislation.gov.uk/uksi/1970/1897/introduction/made|title=The Weights and Measures (Equivalents for dealings with drugs) Regulations 1970|access-date=7 July 2012|archive-date=20 June 2013|archive-url=https://web.archive.org/web/20130620141325/http://www.legislation.gov.uk/uksi/1970/1897/introduction/made|url-status=live}}{{cite web |url=https://www.rpharms.com/Portals/0/MuseumLearningResources/11%20Balances%20Weights%20and%20Measures.pdf |title=Information Sheet: 11: Balances, Weights and Measures |website=Royal Pharmaceutical Society |access-date=11 December 2020 |archive-date=20 May 2022 |archive-url=https://web.archive.org/web/20220520094140/https://www.rpharms.com/Portals/0/MuseumLearningResources/11%20Balances%20Weights%20and%20Measures.pdf |url-status=live }} In the US, though no longer recommended, the apothecaries' system is still used occasionally in medicine, especially in prescriptions for older medications.{{cite book |last=Zentz |first=Lorraine C. |title=Math for Pharmacy Technicians |url=https://books.google.com/books?id=PvriGp6ZEhMC |year=2010 |publisher=Jones & Bartlett Learning |location=Sudbury, MA |isbn=978-0-7637-5961-2 |oclc=421360709 |pages=7–8 |chapter=Chapter 1: Fundamentals of Math – Apothecary System |chapter-url=https://books.google.com/books?id=PvriGp6ZEhMC&pg=PA7 |access-date=1 July 2015 |archive-date=14 January 2023 |archive-url=https://web.archive.org/web/20230114131618/https://books.google.com/books?id=PvriGp6ZEhMC |url-status=live }}{{cite book |last=Boyer |first=Mary Jo |title=Math for Nurses: A Pocket Guide to Dosage Calculation and Drug Preparation |url=https://books.google.com/books?id=FCfCGwqNt4QC |edition=7th |year=2009 |publisher=Wolters Kluwer Health {{pipe}} Lippincott Williams & Wilkins |location=Philadelphia, PA |isbn=978-0-7817-6335-6 |oclc=181600928 |pages=108–9 |chapter=UNIT 2 Measurement Systems: The Apothecary System |chapter-url=https://books.google.com/books?id=FCfCGwqNt4QC&pg=PA108 |access-date=1 July 2015 |archive-date=14 January 2023 |archive-url=https://web.archive.org/web/20230114131618/https://books.google.com/books?id=FCfCGwqNt4QC |url-status=live }}
= Mass and weight =
In the 19th and 20th centuries, the UK used three different systems for mass and weight.
- troy weight, used for precious metals;
- avoirdupois weight, used for most other purposes; and
- apothecaries' weight, now virtually unused since the metric system is used for all scientific purposes.
The distinction between mass and weight is not always clearly drawn. Strictly a pound is a unit of mass, but it is commonly referred to as a weight. When a distinction is necessary, the term pound-force may refer to a unit of force rather than mass. The troy pound ({{val|373.2417216|u=g}}) was made the primary unit of mass by the Weights and Measures Act 1824 and its use was abolished in the UK on 1 January 1879,{{cite book|author=Great Britain|title=Statutes at large ...|url=https://books.google.com/books?id=v39KAAAAMAAJ&pg=PA308|year=1878|page=308}} with only the troy ounce ({{val|31.1034768|u=g}}) and its decimal subdivisions retained.{{Cite EB1911 |wstitle= Weights and Measures |volume= 28 |pages= 477–494; see page 480 |first= Henry James |last= Chaney }} The Weights and Measures Act 1855 made the avoirdupois pound the primary unit of mass.{{cite book|author=Great Britain|title=A collection of public general statutes passed in the 18th and 19th years of the reign of Her Majesty Queen Victoria|url=https://books.google.com/books?id=L1YMAQAAMAAJ&pg=PA273|year=1855|pages=273–75}} In all the systems, the fundamental unit is the pound, and all other units are defined as fractions or multiples of it.
| class="wikitable" style="margin-right:0"
|+ Table of mass units ! Unit ! Pounds ! In SI units ! Notes | ||
| align=center| grain (gr)
|align=right| {{frac|{{val|7000}}}} |align=right| {{val|64.79891|u=mg}} |Exactly {{val|64.79891}} milligrams. | ||
| align=center| drachm (dr)
|align=right| {{frac|256}} |align=right| {{val|1.7718451953125|u=g}} | A dram is {{frac|16}} of an ounce | ||
| align=center| ounce (oz)
|align=right| {{frac|16}} |align=right| {{val|28.349523125|u=g}} | An ounce is {{frac|16}} of a pound | ||
| align=center| pound (lb)
|align=right| 1 |align=right| {{val|0.45359237|u=kg}} |Defined by the Units of Measurement Regulations 1994 (SI 1994/2867){{Cite web|url=http://www.legislation.gov.uk/uksi/1994/2867/schedule/made|title=The Units of Measurement Regulations 1994|website=legislation.gov.uk|language=en|access-date=2019-03-13|archive-date=25 February 2021|archive-url=https://web.archive.org/web/20210225025135/https://www.legislation.gov.uk/uksi/1994/2867/schedule/made|url-status=live}} | ||
| align=center| stone (st)
|align=right| 14 |align=right| {{val|6.35029318|u=kg}} |The plural stone is often used when providing a weight (e.g. "this sack weighs 8 stone").{{Cite web|title = Definition of stone in English from the Oxford dictionary|url = http://www.oxforddictionaries.com/definition/english/stone|archive-url = https://web.archive.org/web/20120711200915/http://oxforddictionaries.com/definition/english/stone|url-status = dead|archive-date = 11 July 2012|website = www.oxforddictionaries.com|publisher = Oxford University Press|access-date = 2015-11-25|ref = stonedefinition}} A person's weight is usually quoted in stone and pounds in English-speaking countries that use the avoirdupois system, with the exception of the United States and Canada, where it is usually quoted in pounds. | ||
| align=center| quarter (qr or qtr)
|align=right| 28 |align=right| {{val|12.70058636|u=kg}} |{{anchor|qtr}} One quarter (literally a quarter of a hundredweight) is equal to two stone or 28 pounds. The term quarter is also used in retail contexts, where it refers to four ounces, i.e. a quarter of a pound. (The 1824 act defined a quarter as a unit of volume, as above: thus a 'quarter of wheat', 64 gallons, would weigh about 494 lb.{{cite web | url= https://www.engineeringtoolbox.com/foods-materials-bulk-density-d_1819.html | title= Bulk densities of some common food products | website= engineeringtoolbox.com | access-date= 19 January 2020 | archive-date= 5 July 2020 | archive-url= https://web.archive.org/web/20200705195715/https://www.engineeringtoolbox.com/foods-materials-bulk-density-d_1819.html | url-status= live }} The density of wheat is 0.770, and 291*0.770={{convert|224|kg}}.). | ||
| align=center| hundredweight (cwt)
|align=right| 112 |align=right| {{val|50.80234544|u=kg}} |One imperial hundredweight is equal to eight stone. This is the long hundredweight, 112 pounds, as opposed to the short hundredweight of 100 pounds used in the United States and Canada.[http://laws-lois.justice.gc.ca/eng/acts/W-6/page-15.html/ Weights and Measures Act] {{Webarchive|url=https://web.archive.org/web/20121016084035/http://laws-lois.justice.gc.ca/eng/acts/W-6/page-15.html/ |date=16 October 2012 }} | ||
| align=center| ton (t{{Citation needed|date=November 2023|reason=Usually "t" stands for "metric ton" (or "tonne"); the article for Long ton states that its abbreviation is "LT" (but also lacks citation)}})
|align=right| 2240 |align=right| {{val|1016.0469088|u=kg}} |Twenty hundredweight equals a ton (as in the US and Canadian systems). The imperial hundredweight is 12% greater than the US and Canadian one. The imperial ton (or long ton) is {{val|2240}} pounds, which is much closer to a tonne (about {{val|2204.6}} pounds), compared to the 10.7% smaller North American short ton of {{convert|2000|lb|kg|3|comma=gaps}}. | ||
| style="text-align:center;" colspan="6"| Gravitational units | ||
| valign=top
|align=center| slug (slug) |align=right| {{val|32.17404856}} |align=right| {{val|14.59390294|u=kg}} |The slug, a unit associated with imperial and US customary systems, is a mass that accelerates by 1 ft/s2 when a force of one pound (lbf) is exerted on it.{{cite web|url=http://www.wolframalpha.com/input/?i=Slug&a=*C.Slug-_*Unit-|title=Wolfram-Alpha: Computational Knowledge Engine|access-date=23 June 2015|archive-date=14 January 2023|archive-url=https://web.archive.org/web/20230114132639/https://www.wolframalpha.com/input/?i=Slug&a=%2AC.Slug-_%2AUnit-|url-status=live}} ::{| | ||
| align=right| F | = ma (Newton's second law) | |
| align=right| 1 lbf | = 1 slug × 1 ft/s2 (as defined above) | |
| align=right| 1 lbf | = 1 lb × g/gc (by definition of the pound force{{citation needed|date=October 2017}}) | |
| align=right| g | ≈ {{val|32.17404856}} ft/s2 | |
| align=right| gc | ≈ {{val|32.17404856}} lbm⋅ft/lbf⋅s2 | |
| ∴ | align=right| 1 slug | ≈ {{val|32.17404856}} pounds |
|}
Natural equivalents
The 1824 Act of Parliament defined the yard and pound by reference to the prototype standards, and it also defined the values of certain physical constants, to make provision for re-creation of the standards if they were to be damaged. For the yard, the length of a pendulum beating seconds at the latitude of Greenwich at mean sea level {{lang|la|in vacuo}} was defined as {{val|39.1393}} inches. For the pound, the mass of a cubic inch of distilled water at an atmospheric pressure of 30 inches of mercury and a temperature of 62° Fahrenheit was defined as 252.458 grains, with there being 7,000 grains per pound.
Following the destruction of the original prototypes in the 1834 Houses of Parliament fire, it proved impossible to recreate the standards from these definitions, and a new Weights and Measures Act 1855 was passed which permitted the recreation of the prototypes from recognized secondary standards.
Current use
=== United Kingdom ===
{{see also|Metrication in the United Kingdom}}
File:Metric_and_imperial_systems_(2019).svg (SI), imperial and US customary systems as of 2019]]
Since the Weights and Measures Act 1985, British law defines base imperial units in terms of their metric equivalent. The metric system is routinely used in business and technology within the United Kingdom, with imperial units remaining in widespread use amongst the public.{{cite news|title=Will British people ever think in metric?|url=https://www.bbc.co.uk/news/magazine-16245391|access-date=26 February 2017|publisher=BBC|date=21 December 2011|first=Jon|last=Kelly|quote=...but today the British remain unique in Europe by holding onto imperial weights and measures. ...the persistent British preference for imperial over metric is particularly noteworthy...|archive-date=24 April 2012|archive-url=https://web.archive.org/web/20120424232814/http://www.bbc.co.uk/news/magazine-16245391|url-status=live}} All UK roads use the imperial system except for weight limits, and newer height or width restriction signs give metric alongside imperial.{{cite news|title=Height and width road signs to display metric and imperial|url=https://www.bbc.com/news/uk-29965935|access-date=26 February 2017|publisher=BBC|date=8 November 2014|quote=New road signs showing height and width restrictions will use both metric and imperial measurements from March 2015....Road signs for bridges, tunnels and narrow roads can currently show measurements in just feet and inches or only metres. Some already display both.|archive-date=26 February 2017|archive-url=https://web.archive.org/web/20170226222752/http://www.bbc.com/news/uk-29965935|url-status=live}}File:MetricImperialUSCustomaryUnits.jpg
Traders in the UK may accept requests from customers specified in imperial units, and scales which display in both unit systems are commonplace in the retail trade. Metric price signs may be accompanied by imperial price signs provided that the imperial signs are no larger and no more prominent than the metric ones.
The United Kingdom completed its official partial transition to the metric system in 1995, with imperial units still legally mandated for certain applications such as draught beer and cider,{{cite web |url=http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1073792198 |archive-url=https://web.archive.org/web/20110720114311/http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1073792198 |archive-date=2011-07-20 |title=BusinessLink: Weights and measures: Rules for pubs, restaurants and cafes|access-date=24 August 2009|format=online |publisher= Department for Business, Innovation & Skills }} and road-signs.{{cite web |url=http://www.bwmaonline.com/Transport%20-%20DfT%20memo.htm |title=Department for Transport statement on metric road signs |access-date=24 August 2009 |date=12 July 2002 |format=online |publisher=BWMA |archive-date=25 May 2009 |archive-url=https://web.archive.org/web/20090525082727/http://www.bwmaonline.com/Transport%20-%20DfT%20memo.htm |url-status=live }} Therefore, the speedometers on vehicles sold in the UK must be capable of displaying miles per hour. Even though the troy pound was outlawed in the UK in the Weights and Measures Act 1878, the troy ounce may still be used for the weights of precious stones and metals. The original railways (many built in the Victorian era) are a big user of imperial units, with distances officially measured in miles and yards or miles and chains, and also feet and inches, and speeds are in miles per hour.
Some British people still use one or more imperial units in everyday life for distance (miles, yards, feet, and inches) and some types of volume measurement (especially milk and beer in pints; rarely for canned or bottled soft drinks, or petrol).{{cite news |work=The Guardian |date=1 December 2006 |title=In praise of ... metric measurements |url=https://www.theguardian.com/commentisfree/2006/dec/01/comment.britishidentity |location=London |access-date=29 October 2017 |archive-date=19 September 2017 |archive-url=https://web.archive.org/web/20170919233902/https://www.theguardian.com/commentisfree/2006/dec/01/comment.britishidentity |url-status=live }} {{As of|February 2021}}, many British people also still use imperial units in everyday life for body weight (stones and pounds for adults, pounds and ounces for babies).{{cite web |url=https://moneyweek.com/economy/uk-economy/602705/decimalisation-britains-new-pence-turn-50-years-old |title=Decimalisation: Britain's "new pence" turn 50 years old |last=King |first=Max |date=15 February 2021 |work=MoneyWeek |access-date=8 April 2021 |archive-date=15 May 2021 |archive-url=https://web.archive.org/web/20210515143311/https://moneyweek.com/economy/uk-economy/602705/decimalisation-britains-new-pence-turn-50-years-old |url-status=live }} Government documents aimed at the public may give body weight and height in imperial units as well as in metric.{{cite web |title=BMI healthy weight calculator |url=http://www.nhs.uk/Tools/Documents/BMI%20Healthy%20weight%20calculator.htm |publisher=National Health Service |access-date=25 November 2015 |archive-date=19 January 2016 |archive-url=https://web.archive.org/web/20160119013839/http://www.nhs.uk/Tools/Documents/BMI%20Healthy%20weight%20calculator.htm |url-status=live }} A survey in 2015 found that many people did not know their body weight or height in both systems.{{Cite web|access-date=29 October 2017|date=20 June 2015|first1=Will|last1=Dahlgreen|url=https://yougov.co.uk/news/2015/06/20/britains-metric-muddle/|title=Britain's metric muddle not changing any time soon|quote=even today [2015] some 18-24-year-olds still do not know how much they weigh in kilograms (60%) or how tall they are in metres and centimetres (54%).|archive-date=30 October 2017|archive-url=https://web.archive.org/web/20171030003336/https://yougov.co.uk/news/2015/06/20/britains-metric-muddle/|url-status=live}} As of 2017, people under the age of 40 preferred the metric system but people aged 40 and over preferred the imperial system.{{Cite web|access-date=29 October 2017|date=2015|url=https://d25d2506sfb94s.cloudfront.net/cumulus_uploads/document/vsi5u7fi74/InternalResults_150609_systems_of_measurement_Website.pdf|title=YouGov Survey Results|archive-date=30 October 2017|archive-url=https://web.archive.org/web/20171030003559/https://d25d2506sfb94s.cloudfront.net/cumulus_uploads/document/vsi5u7fi74/InternalResults_150609_systems_of_measurement_Website.pdf|url-status=live}} As in other English-speaking countries, including Australia, Canada and the United States, the height of horses is usually measured in hands, standardised to {{Convert|4|in|sigfig=3}}. Fuel consumption for vehicles is commonly stated in miles per gallon (mpg), though official figures always include litres per {{Val|100|u=km}} equivalents and fuel is sold in litres. When sold draught in licensed premises, beer and cider must be sold in pints, half-pints or third-pints.{{Cite web|url=https://www.gov.uk/weights-measures-and-packaging-the-law/specified-quantities|title=Weights and measures: the law|date=7 April 2020|website=gov.uk|access-date=7 April 2020|archive-date=2 October 2015|archive-url=https://web.archive.org/web/20151002115839/https://www.gov.uk/weights-measures-and-packaging-the-law/specified-quantities|url-status=live}} Cow's milk is available in both litre- and pint-based containers in supermarkets and shops. Areas of land associated with farming, forestry and real estate are commonly advertised in acres and square feet but, for contracts and land registration purposes, the units are always hectares and square metres.{{Cite web | url= http://www.legislation.gov.uk/uksi/2009/3045/pdfs/uksiem_20093045_en.pdf | year= 2009 | title= Explanatory memorandum to The weights and measures (metrication amendments) regulations 2009 | publisher= Legislation.gov.uk | access-date= 3 November 2019 | archive-date= 4 March 2021 | archive-url= https://web.archive.org/web/20210304074504/https://www.legislation.gov.uk/uksi/2009/3045/pdfs/uksiem_20093045_en.pdf | url-status= live }} See paragraph 7.4.
Office space and industrial units are usually advertised in square feet. Steel pipe sizes are sold in increments of inches, while copper pipe is sold in increments of millimetres. Road bicycles have their frames measured in centimetres, while off-road bicycles have their frames measured in inches. Display sizes for screens on television sets and computer monitors are always diagonally measured in inches. Food sold by length or width, e.g. pizzas or sandwiches, is generally sold in inches. Clothing is usually sized in inches, with the metric equivalent often shown as a small supplementary indicator. Gas is usually measured by the cubic foot or cubic metre, but is billed like electricity by the kilowatt hour.{{cite web|url=https://www.gov.uk/guidance/gas-meter-readings-and-bill-calculation|title=Gas meter readings and bill calculation|website=gov.uk|access-date=15 December 2016|archive-date=20 December 2016|archive-url=https://web.archive.org/web/20161220171928/https://www.gov.uk/guidance/gas-meter-readings-and-bill-calculation|url-status=live}}
Pre-packaged products can show both metric and imperial measures, and it is also common to see imperial pack sizes with metric only labels, e.g. a {{cvt|1|lb|g|0}} tin of Lyle's Golden Syrup is always labelled {{Val|454|u=g}} with no imperial indicator. Similarly most jars of jam and packs of sausages are labelled {{Val|454|u=g}} with no imperial indicator.
=India=
{{main|Metrication in India}}
India began converting to the metric system from the imperial system between 1955 and 1962. The metric system in weights and measures was adopted by the Indian Parliament in December 1956 with the Standards of Weights and Measures Act, which took effect beginning 1 October 1958. By 1962, metric units became "mandatory and exclusive."{{cite journal |last1=Velkar |first1=Ashish |title=Rethinking Metrology, Nationalism and Development in India, 1833–1956 |journal=Past & Present |date=May 2018 |issue=239 |pages=143–79 |doi=10.1093/pastj/gtx064 |url=https://www.research.manchester.ac.uk/portal/files/65152126/Past_Present_Author_Accepted_Version.pdf |access-date=30 April 2022 |archive-date=29 May 2022 |archive-url=https://web.archive.org/web/20220529075121/https://www.research.manchester.ac.uk/portal/files/65152126/Past_Present_Author_Accepted_Version.pdf |url-status=live }}
Today all official measurements are made in the metric system. In common usage some older Indians may still refer to imperial units. Some measurements, such as the heights of mountains, are still recorded in feet. Tyre rim diameters are still measured in inches, as used worldwide. Industries like the construction and the real estate industry still use both the metric and the imperial system though it is more common for sizes of homes to be given in square feet and land in acres.Acharya, Anil Kumar. History of Decimalisation Movement in India, Auto-Print & Publicity House, 1958.
In Standard Indian English, as in Australian, Canadian, New Zealand, Singaporean, and British English, metric units such as the litre, metre, and tonne utilise the traditional spellings brought over from French, which differ from those used in the United States and the Philippines. The imperial long ton is invariably spelt with one 'n'.
=Hong Kong=
Hong Kong has three main systems of units of measurement in current use:
- The Chinese units of measurement of the Qing Empire (no longer in widespread use in China);
- British imperial units; and
- The metric system.
In 1976 the Hong Kong Government started the conversion to the metric system, and as of 2012 measurements for government purposes, such as road signs, are almost always in metric units. All three systems are officially permitted for trade,{{cite web|url=http://www.hklii.hk/eng/hk/legis/ord/68/sch2.html|title=CAP 68 WEIGHTS AND MEASURES ORDINANCE Sched 2 UNITS OF MEASUREMENT AND PERMITTED SYMBOLS OR ABBREVIATIONS OF UNITS OF MEASUREMENT LAWFUL FOR USE FOR TRADE|access-date=31 January 2015|archive-date=3 September 2015|archive-url=https://web.archive.org/web/20150903233217/http://www.hklii.hk/eng/hk/legis/ord/68/sch2.html|url-status=live}} and in the wider society a mixture of all three systems prevails.
The Chinese system's most commonly used units for length are {{lang|zh|里}} (lei5), {{lang|zh|丈}} (zoeng6), {{lang|zh|尺}} (cek3), {{lang|zh|寸}} (cyun3), {{lang|zh|分}} (fan1) in descending scale order. These units are now rarely used in daily life, the imperial and metric systems being preferred. The imperial equivalents are written with the same basic Chinese characters as the Chinese system. In order to distinguish between the units of the two systems, the units can be prefixed with "Ying" ({{lang|zh|英}}, jing1) for the imperial system and "Wa" ({{lang|zh|華}}, waa4) for the Chinese system. In writing, derived characters are often used, with an additional {{lang|zh|口}} (mouth) radical to the left of the original Chinese character, for writing imperial units. The most commonly used units are the mile or "li" ({{lang|zh|哩}}, li1), the yard or "ma" ({{lang|zh|碼}}, maa5), the foot or "chek" ({{lang|zh|呎}}, cek3), and the inch or "tsun" ({{lang|zh|吋}}, cyun3).
The traditional measure of flat area is the square foot ({{lang|zh|方呎, 平方呎}}, fong1 cek3, ping4 fong1 cek3) of the imperial system, which is still in common use for real estate purposes. The measurement of agricultural plots and fields is traditionally conducted in {{lang|zh|畝}} (mau5) of the Chinese system.
For the measurement of volume, Hong Kong officially uses the metric system, though the gallon ({{lang|zh|加侖}}, gaa1 leon4-2) is also occasionally used.
= Canada =
{{See also|Metrication in Canada}}
File:Canadian canned food labels showing imperial and metric units of measurement.jpg
During the 1970s, the metric system and SI units were introduced in Canada to replace the imperial system. Within the government, efforts to implement the metric system were extensive; almost any agency, institution, or function provided by the government uses SI units exclusively. Imperial units were eliminated from all public road signs and both systems of measurement will still be found on privately owned signs, such as the height warnings at the entrance of a parkade. In the 1980s, momentum to fully convert to the metric system stalled when the government of Brian Mulroney was elected. There was heavy opposition to metrication and as a compromise the government maintains legal definitions for and allows use of imperial units as long as metric units are shown as well.
{{cite web
|url=http://laws.justice.gc.ca/en/showdoc/cs/W-6/sc:2//en#anchorsc:2
|title=Weights and Measures Act: Canadian units of measure
|publisher=Justice Canada
|access-date=14 November 2007
|url-status=dead|archive-url=https://web.archive.org/web/20110605042528/http://laws.justice.gc.ca/en/showdoc/cs/W-6/sc%3A2//en
|archive-date=5 June 2011
{{cite book
|chapter-url=http://www.inspection.gc.ca/english/fssa/labeti/guide/ch11e.shtml#11.2
|title=Guide to Food Labelling and Advertising
|chapter=11
|publisher=Canadian Food Inspection Agency
|access-date=1 December 2007
|url-status=dead
|archive-url=https://web.archive.org/web/20080124081159/http://www.inspection.gc.ca/english/fssa/labeti/guide/ch11e.shtml
|archive-date=24 January 2008
|url=http://lois-laws.justice.gc.ca/eng/regulations/C.R.C.,_c._417/
|title=Consumer Packaging and Labelling Regulations (C.R.C., c. 417)
|access-date=15 November 2012
|publisher=Justice Canada, Legislative Services Branch
|archive-date=27 December 2012
|archive-url=https://web.archive.org/web/20121227050045/http://lois-laws.justice.gc.ca/eng/regulations/C.R.C.%2C%5Fc.%5F417/
|url-status=live
|url=https://www.ic.gc.ca/eic/site/mc-mc.nsf/eng/lm04293.html#Part3SectionA
|title=Field Inspection Manual — Automatic Weighing Devices: Part 3, Section A: Abbreviations and Symbols Accepted in Canada
|date=2 February 2017
|access-date=21 July 2022
|archive-date=26 August 2022
|archive-url=https://web.archive.org/web/20220826160500/https://www.ic.gc.ca/eic/site/mc-mc.nsf/eng/lm04293.html#Part3SectionA
|url-status=live
}}
The law requires that measured products (such as fuel and meat) be priced in metric units and an imperial price can be shown if a metric price is present.
{{cite web |url=http://archives.cbc.ca/clip.asp?page=1&IDLan=1&IDClip=10620&IDCat=345&IDCatPa=261 |title=A Canadian compromise |access-date=11 March 2008 |publisher=CBC |date=30 January 1985 |archive-url=https://web.archive.org/web/20090116024023/http://archives.cbc.ca/clip.asp?page=1&IDLan=1&IDClip=10620&IDCat=345&IDCatPa=261 |archive-date=2009-01-16}}
{{cite web |url=http://archives.radio-canada.ca/clip.asp?page=1&IDLan=0&IDClip=9378&IDCat=216&IDCatPa=151 |title=Les livres et les pieds, toujours présents (eng:The pounds and feet, always present) |access-date=11 March 2008 |publisher=5 sur 5, Société Radio-Canada |language=fr |archive-date=6 June 2011 |archive-url=https://web.archive.org/web/20110606173005/http://archives.radio-canada.ca/clip.asp?page=1&IDLan=0&IDClip=9378&IDCat=216&IDCatPa=151 |url-status=dead }} There tends to be leniency in regards to fruits and vegetables being priced in imperial units only.
Environment Canada still offers an imperial unit option beside metric units, even though weather is typically measured and reported in metric units in the Canadian media. Some radio stations near the United States border (such as CIMX and CIDR) primarily use imperial units to report the weather. Railways in Canada also continue to use imperial units.
Imperial units are still used in ordinary conversation. Today, Canadians typically use a mix of metric and imperial measurements in their daily lives. The use of the metric and imperial systems varies by age. The older generation mostly uses the imperial system, while the younger generation more often uses the metric system. Quebec has implemented metrication more fully. {{citation needed |date=July 2019}} Newborns are measured in SI at hospitals, but the birth weight and length is also announced to family and friends in imperial units. Drivers' licences use SI units, though many English-speaking Canadians give their height and weight in imperial. In livestock auction markets, cattle are sold in dollars per hundredweight (short), whereas hogs are sold in dollars per hundred kilograms. Imperial units still dominate in recipes, construction, house renovation and gardening.{{cite web|url=http://www.bwmaonline.com/Imperial%20Origins.htm|title=Imperial Measures - The Origins|publisher=British Weights and Measures Association|website=BWMAOnline.com|date=15 February 2021|access-date=5 March 2011|archive-date=15 May 2011|archive-url=https://web.archive.org/web/20110515101232/http://www.bwmaonline.com/Imperial%20Origins.htm|url-status=live}}{{cite news|url=https://www.pressreader.com/canada/national-post-latest-edition/20110222/283661116291286|title=Crepes worth savouring|work=National Post|via=PressReader.com|first=Amy|last=Rosen|date=23 February 2011|access-date=11 July 2019|archive-date=11 July 2019|archive-url=https://web.archive.org/web/20190711135613/https://www.pressreader.com/canada/national-post-latest-edition/20110222/283661116291286|url-status=live}}{{cite news|url=https://www.pressreader.com/canada/national-post-national-edition/20110201/283403418230709|title=Scoring brownie points|work=National Post|via=PressReader.com|first=Amy|last=Rosen|date=2 February 2011|access-date=11 July 2019|archive-date=11 July 2019|archive-url=https://web.archive.org/web/20190711135612/https://www.pressreader.com/canada/national-post-national-edition/20110201/283403418230709|url-status=live}}{{cite news|url=https://nationalpost.com/news/drinking-school/wcm/f22ca2bc-5ad6-4a50-a8c9-eee40d832521|title=Drinking school|work=National Post|first=Adam|last=McDowell|date=28 February 2011}}{{cite web|url=http://www.homehardware.ca/en/cat/index.htm/Building-Supplies/Building-Materials/Fence-Products/_/N-nthr4|title=Home Hardware - Building Supplies - Building Materials - Fence Products|access-date=5 March 2011|archive-url=https://web.archive.org/web/20110629070126/http://www.homehardware.ca/en/cat/index.htm/Building-Supplies/Building-Materials/Fence-Products/_/N-nthr4|archive-date=29 June 2011|url-status=dead}} Land is now surveyed and registered in metric units whilst initial surveys used imperial units. For example, partitioning of farmland on the prairies in the late 19th and early 20th centuries was done in imperial units; this accounts for imperial units of distance and area retaining wide use in the Prairie Provinces.
In English-speaking Canada commercial and residential spaces are mostly (but not exclusively) constructed using square feet, while in French-speaking Quebec commercial and residential spaces are constructed in metres and advertised using both square metres and square feet as equivalents. Carpet or flooring tile is purchased by the square foot, but less frequently also in square metres.{{cite web| url = https://www.tripadvisor.com/Travel-g153339-c15311/Canada:Metric.System.html| title = Canada: Metric System| access-date = 24 February 2020| archive-date = 13 February 2020| archive-url = https://web.archive.org/web/20200213223443/https://www.tripadvisor.com/Travel-g153339-c15311/Canada:Metric.System.html| url-status = live}}{{cite news|url=http://www.lapresse.ca/vivre/societe/201508/25/01-4895245-systeme-metrique-a-quand-le-virage-final.php|title=Système métrique: à quand le virage final?|first=Marie|last=Allard|work=LaPresse.ca|date=2015-08-25|language=fr|access-date=24 February 2020|archive-date=24 February 2020|archive-url=https://web.archive.org/web/20200224085807/https://www.lapresse.ca/vivre/societe/201508/25/01-4895245-systeme-metrique-a-quand-le-virage-final.php|url-status=live}} Motor-vehicle fuel consumption is reported in both litres per {{Val|100|u=km}} and statute miles per imperial gallon,{{cite web|url=http://www.oee.nrcan.gc.ca/transportation/tools/fuelratings/ratings-search.cfm?attr=8|title=Fuel Consumption Ratings Search Tool - Conventional Vehicles|first=Government of Canada, Natural Resources|last=Canada|access-date=15 January 2009|archive-date=6 July 2011|archive-url=https://web.archive.org/web/20110706181822/http://www.oee.nrcan.gc.ca/transportation/tools/fuelratings/ratings-search.cfm?attr=8|url-status=dead}} leading to the erroneous impression that Canadian vehicles are 20% more fuel-efficient than their apparently identical American counterparts for which fuel economy is reported in statute miles per US gallon (neither country specifies which gallon is used). Canadian railways maintain exclusive use of imperial measurements to describe train length (feet), train height (feet), capacity (tons), speed (mph), and trackage (miles).{{cite web|url=http://www.tsb.gc.ca/eng/rapports-reports/rail/1996/r96w0171/r96w0171.asp|title=Railway Investigation Report R96W0171|first=Government of Canada, Transportation Safety Board of|last=Canada|date=9 April 1999|access-date=5 March 2011|archive-date=6 July 2011|archive-url=https://web.archive.org/web/20110706181813/http://www.tsb.gc.ca/eng/rapports-reports/rail/1996/r96w0171/r96w0171.asp|url-status=live}}
Imperial units also retain common use in firearms and ammunition. Imperial measures are still used in the description of cartridge types, even when the cartridge is of relatively recent invention (e.g., .204 Ruger, .17 HMR, where the calibre is expressed in decimal fractions of an inch). Ammunition that is already classified in metric is still kept metric (e.g., 9×19mm). In the manufacture of ammunition, bullet and powder weights are expressed in terms of grains for both metric and imperial cartridges.
In keeping with the international standard, air navigation is based on nautical units, e.g., the nautical mile, which is neither imperial nor metric, and altitude is measured in imperial feet.{{cite web|url=http://www.langleyflyingschool.com/Pages/Canadian%20Aviation%20Regulations.html#Altimeter%20Rules|title=Canadian Aviation Regulations|website=Langley Flying School|at=sec. "Altimeter Rules"|access-date=14 May 2014|archive-date=14 May 2014|archive-url=https://web.archive.org/web/20140514113051/http://www.langleyflyingschool.com/Pages/Canadian%20Aviation%20Regulations.html#Altimeter%20Rules|url-status=live}}
=Australia=
{{Main|Metrication in Australia}}
While metrication in Australia has largely ended the official use of imperial units, for particular measurements, international use of imperial units is still followed.
- In licensed venues, draught beer and cider is sold in glasses and jugs with sizes based on the imperial fluid ounce, though rounded to the nearest 5 mL.
- Newborns are measured in metric at hospitals, but the birth weight and length is sometimes also announced to family and friends in imperial units.
- Screen sizes, are frequently described in inches instead of or as well as centimetres.
- Property size is infrequently described in acres, but is mostly as square metres or hectares.
- Marine navigation is done in nautical miles, and water-based speed limits are in nautical miles per hour.
- Historical writing and presentations may include pre-metric units to reflect the context of the era represented.
- The illicit drug trade in Australia still often uses imperial measurements, particularly when dealing with smaller amounts closer to end user levels e.g. "8-ball" an 8th of an ounce or {{Val|3.5|u=g}}; cannabis is often traded in ounces ("oz") and pounds ("p"){{cn|reason=for 'p' representing 'lb'|date=May 2023}}
- Firearm barrel length are almost always referred by in inches, ammunition is also still measured in grains and ounces as well as grams.
- A persons height is frequently and informally described in feet and inches, but on official records is described in metres.
The influence of British and American culture in Australia has been noted to be a cause for residual use of imperial units of measure.
=New Zealand=
{{Main|Metrication in New Zealand}}
New Zealand introduced the metric system on 15 December 1976.{{cite web| url = https://www.beehive.govt.nz/release/30-years-metric-system| title = "30 Years of the Metric System"| access-date = 4 February 2021| archive-date = 9 February 2021| archive-url = https://web.archive.org/web/20210209075115/https://www.beehive.govt.nz/release/30-years-metric-system| url-status = live}} Aviation was exempt, with altitude and airport elevation continuing to be measured in feet whilst navigation is done in nautical miles; all other aspects (fuel quantity, aircraft weight, runway length, etc.) use metric units.
Screen sizes for devices such as televisions, monitors and phones, and wheel rim sizes for vehicles, are stated in inches, as is the convention in the rest of the world - and a 1992 study found a continued use of imperial units for birth weight and human height alongside metric units.[http://www.psychology.org.nz/cms_show_download.php?id=785 "Human use of metric measures of length"] {{webarchive |url=https://web.archive.org/web/20130209034410/http://www.psychology.org.nz/cms_show_download.php?id=785 |date=9 February 2013 }}. Dignan, J. R. E., & O'Shea, R. P. (1995). New Zealand Journal of Psychology, 24, 21–25.
=Ireland=
{{Main|Metrication in Ireland}}
Ireland has officially changed over to the metric system since entering the European Union, with distances on new road signs being metric since 1997 and speed limits being metric since 2005. The imperial system remains in limited use – for sales of beer in pubs (traditionally sold by the pint). All other goods are required by law to be sold in metric units with traditional quantities being retained for goods like butter and sausages, which are sold in {{Convert|454|g|lb|0}} packaging. The majority of cars sold pre-2005 feature speedometers with miles per hour as the primary unit, but with a kilometres per hour display. Often signs such as those for bridge height can display both metric and imperial units. Imperial measurements continue to be used colloquially by the general population especially with height and distance measurements such as feet, inches, and acres as well as for weight with pounds and stones still in common use among people of all ages. Measurements such as yards have fallen out of favour with younger generations. Ireland's railways still use imperial measurements for distances and speed signage.{{Cite web|title=Republic of Ireland|url=http://www.railsigns.uk/overseas/ireland2/ireland2.html|access-date=2021-02-22|publisher=www.railsigns.uk|archive-date=23 October 2021|archive-url=https://web.archive.org/web/20211023194641/http://www.railsigns.uk/overseas/ireland2/ireland2.html|url-status=dead}}{{Cite web|title=Network Statement 2022|url=https://www.irishrail.ie/Admin/getmedia/41c1078d-a0e8-42c5-84c4-08bc8c063e0f/IE-2022-Network-Statement.pdf|publisher=Irish Rail|access-date=2022-02-24|language=en|archive-date=19 January 2022|archive-url=https://web.archive.org/web/20220119133324/https://www.irishrail.ie/Admin/getmedia/41c1078d-a0e8-42c5-84c4-08bc8c063e0f/IE-2022-Network-Statement.pdf|url-status=live}} Property is usually listed in square feet as well as metres also.
Horse racing in Ireland still continues to use stones, pounds, miles and furlongs as measurements.{{cite web| url = http://www.hri-ras.ie/information-centre/hri-directives-and-rules/full/| url-status = dead| archive-url = https://web.archive.org/web/20160504050454/http://www.hri-ras.ie/information-centre/hri-directives-and-rules/full/| archive-date = 4 May 2016| title = Full HRI Directives}}
=Bahamas=
Imperial measurements remain in general use in the Bahamas.
Legally, both the imperial and metric systems are recognised by the Weights and Measures Act 2006.{{cite web |author1=Parliament of the Bahamas |title=Weights and Measures Act 2006 |url=https://www.bbsq.bs/en/files/acts-and-regulations/1-weights-and-measures-act/file |website=Bahamas Bureau of Standards and Quality |access-date=24 September 2021 |archive-date=2 June 2021 |archive-url=https://web.archive.org/web/20210602215910/https://www.bbsq.bs/en/files/acts-and-regulations/1-weights-and-measures-act/file |url-status=live }}
=Belize=
Both imperial units and metric units are used in Belize. Both systems are legally recognized by the National Metrology Act.{{cite web |title=National Metrology Act, Chapter 294, Revised Edition 2011 |url=https://bbs.gov.bz/wp-content/uploads/2016/11/Cap-294-National-Metrology-Act.pdf |publisher=Government of Belize |access-date=11 January 2024}}
=Myanmar=
{{Main|Myanmar units of measurement}}
According to the CIA, in June 2009, Myanmar was one of three countries that had not adopted the SI metric system as their official system of weights and measures.{{cite web |url=https://www.cia.gov/library/publications/the-world-factbook/appendix/print_appendix-g.html |title=The World Factbook, Appendix G: Weights and Measures |year=2010 |work=Web Pages |publisher=Central Intelligence Agency |access-date=10 May 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100528121337/https://www.cia.gov/library/publications/the-world-factbook/appendix/print_appendix-g.html |archive-date=28 May 2010 |df=dmy-all }}{{Unreliable source?|date=August 2023}} Metrication efforts began in 2011.{{cite news|last= Gyi|first= Ko Ko |others= Translated by Thit Lwin|date=18-24 July 2011|title= Ditch the viss, govt urges traders|department=Business and Property|url= http://www.mmtimes.com/2011/business/584/biz58401.html |url-status=dead|work=The Myanmar Times |location=Myanmar |archive-url=https://web.archive.org/web/20110920011617/http://www.mmtimes.com/2011/business/584/biz58401.html |archive-date=2011-09-20|access-date=2023-03-04}} The Burmese government set a goal to metricate by 2019, which was not met, with the help of the German National Metrology Institute.{{cite news|url= http://mizzima.com/opinion/features/item/10955-metrication-in-myanmar |title= Metrication in Myanmar |website= Mizzima News |first= Nicholas |last= Kohler |date= 3 March 2014 |archive-url= https://web.archive.org/web/20141216042534/http://mizzima.com/opinion/features/item/10955-metrication-in-myanmar |archive-date= 16 December 2014 |url-status= dead | access-date= 20 April 2015}}
=Other countries=
Some imperial measurements remain in limited use in Malaysia, the Philippines, Sri Lanka and South Africa. Measurements in feet and inches, especially for a person's height, are frequently encountered in conversation and non-governmental publications.
Prior to metrication, it was a common practice in Malaysia for people to refer to unnamed locations and small settlements along major roads by referring to how many miles the said locations were from the nearest major town. In some cases, these eventually became the official names of the locations; in other cases, such names have been largely or completely superseded by new names. An example of the former is Batu 32 (literally "Mile 32" in Malay), which refers to the area surrounding the intersection between Federal Route 22 (the Tamparuli-Sandakan highway) and Federal Route 13 (the Sandakan-Tawau highway). The area is so named because it is 32 miles west of Sandakan, the nearest major town.
Petrol is still sold by the imperial gallon in Anguilla, Antigua and Barbuda, Belize, Myanmar, the Cayman Islands, Dominica, Grenada, Montserrat, St Kitts and Nevis and St. Vincent and the Grenadines.{{cn|date=August 2023}} The United Arab Emirates Cabinet in 2009 issued the Decree No. (270 / 3) specifying that, from 1 January 2010, the new unit sale price for petrol will be the litre and not the gallon, which was in line with the UAE Cabinet Decision No. 31 of 2006 on the national system of measurement, which mandates the use of International System of units as a basis for the legal units of measurement in the country.{{cite web|url=http://agriculture.gov.gd/newsitem.aspx?nid=375 |publisher=The Ministry of Agriculture, Government of Grenada |date=2004-11-01 |title=Address by Agriculture Minister Gregory Bowen |access-date=15 January 2008 |quote=The price of gasoline at the pumps was fixed at EC$7.50 per imperial gallon... |archive-url=https://web.archive.org/web/20080324183215/http://agriculture.gov.gd/newsitem.aspx?nid=375 |archive-date=24 March 2008 }}{{cite web|url=http://mof.gov.bz/faqresults.asp?category=SUPPLIES+CONTROL&question=39 |title=FAQ |website=MoF.gov.bz |access-date=15 January 2008 |publisher=Belize Ministry of Finance |archive-url=https://web.archive.org/web/20080123210505/http://mof.gov.bz/faqresults.asp?category=SUPPLIES+CONTROL&question=39 |archive-date=2008-01-23 |quote=• Kerosene per US Gallon (per Imperial gallon) • Gasoline (Regular)(per imperial Gallon) • Gasoline (Premium) (per Imperial Gallon) • Diesel (per Imperial Gallon) }}{{cite web|url=http://www.antigua-barbuda.com/business_politics/budget_speeches/budget_speech_2001.asp |title=The High Commission Antigua and Barbuda |access-date=15 January 2008 |url-status=dead|archive-url=https://web.archive.org/web/20090131213551/http://www.antigua-barbuda.com/business_politics/budget_speeches/budget_speech_2001.asp |archive-date=31 January 2009}}{{cite web|url=http://www.international-fuel-prices.com/downloads/FuelPrices2005.pdf |title=International Fuel Prices 2005 |website=International-Fuel-Prices.com |first=Gerhard P. |last=Metschies |date=6 September 2005 |access-date=15 January 2008 |page=96 |publisher=German Technical Cooperation |archive-url=https://web.archive.org/web/20070207130929/http://www.international-fuel-prices.com/downloads/FuelPrices2005.pdf |archive-date=2007-02-07}} Sierra Leone switched to selling fuel by the litre in May 2011.{{cite web|publisher=Sierra Leone Embassy in the United States|url=http://embassyofsierraleone.net/node/54|title=Introduction of the Metric System and the Price of Petroleum Products|archive-url=https://web.archive.org/web/20150429165159/http://embassyofsierraleone.net/node/54|archive-date=29 April 2015|access-date=23 October 2011}}
In October 2011, the Antigua and Barbuda government announced the re-launch of the Metrication Programme in accordance with the Metrology Act 2007, which established the International System of Units as the legal system of units. The Antigua and Barbuda government has committed to a full conversion from the imperial system by the first quarter of 2015.{{cite news|title=Minister Lovell Addresses Metric Conversions |url=http://www.caribarena.com/antigua/news/economy/98673-minister-lovell-addresses-metric-conversions.html |newspaper=CARIBARENA Antigua |date=18 October 2011 |access-date=23 October 2011 |url-status=dead|archive-url=https://web.archive.org/web/20111020040638/http://www.caribarena.com/antigua/news/economy/98673-minister-lovell-addresses-metric-conversions.html |archive-date=20 October 2011}}
See also
Explanatory notes
{{reflist|group=nb}}
Citations
{{Reflist|30em}}
General sources
- Appendices B and C of [https://web.archive.org/web/20050403211923/http://ts.nist.gov/ts/htdocs/230/235/h442003.htm NIST Handbook 44]
- {{cite web |first1=A. |last1=Thompson |first2=Barry N. |last2=Taylor |url=http://physics.nist.gov/Pubs/SP811/ |title=The NIST guide for the use of the international system of units |publisher=NIST |date=5 October 2010 |access-date=15 October 2012 |archive-url=https://web.archive.org/web/20100216211152/http://physics.nist.gov/Pubs/SP811/ |archive-date=16 February 2010 |url-status=dead}} Also available as a [http://physics.nist.gov/cuu/pdf/sp811.pdf PDF file].
- 6 George IV chapter 12, 1825 (statute)
External links
{{Commons category|British Imperial units}}
- [http://bwma.org.uk British Weights And Measures Association]
- [https://archive.today/20070224102425/http://laws.justice.gc.ca/en/ShowFullDoc/cs/W-6///en Canada Weights and Measures Act 1970-71-72]
- [https://web.archive.org/web/20061126120208/http://ts.nist.gov/WeightsAndMeasures/Publications/upload/h4402_appenc.pdf General table of units of measure – NIST – pdf]
- [http://www.unc.edu/~rowlett/units/ How Many? A Dictionary of Units of Measurement] {{Webarchive|url=https://web.archive.org/web/20181010153750/http://www.unc.edu/~rowlett/units/ |date=10 October 2018 }}
- {{UK SI|year=1995|number=1804|title=Units of Measurement Regulations 1995}}
{{Imperial units|state=expanded}}
{{systems of measurement}}
{{Authority control}}