7 mm scale
{{Needs more references|date=January 2014}}
{{Infobox model rail scale
| name =7 mm scale
| image_filename = Locomotor model.jpg
| image_caption = O gauge layout at the Trains and Boats exhibition
| widthpx = 270 px
| scale = 7 mm to 1 ft
| standard =
| ratio = 1:43.5
| gauge = multiple
| prototype_gauge =
| note =
| website =
}}
7 mm scale, also known as British O scale is a model railway scale of 1:43.5 (or 7 mm to 1 ft; hence its name). The scale is thus different from American O scale (1:48) and European O scale (1:45). For standard gauge railways, 32mm gauge, or 0 gauge is most commonly used. ScaleSeven (S7) standard however specifies 33 mm gauge, which is closer to scale.{{cite web |title=Model Railway Scales and gauges explained |url=https://www.world-of-railways.co.uk/techniques/model-railway-scales-and-gauges-explained/ |website=World of Railways |access-date=10 November 2024 |date=16 January 2019}} For narrow gauge modelling, 16.5 mm gauge
| class=wikitable
! Name !! Model gauge !! Scaled gauge !! Prototype gauge | |||
| colspan=4 style="text-align:left;" | Prototype standard gauges | |||
|---|---|---|---|
| British 0 gauge | 32 mm (0 gauge) | 4' 6¾"{{cn|date=February 2016}} | Standard gauge |
| ScaleSeven (standard) | 33 mm | 4' 8½" | {{RailGauge|ussg|allk=on}} |
| colspan=4 style="text-align:left;" | Prototype broad gauges | |||
| ScaleSeven (Irish) | 36.75 mm | 5' 3" | {{RailGauge|Irish|allk=on}} |
| ScaleSeven (Great Western) | 49.2 mm | 7' 0¼" | {{RailGauge|brunel}} Great Western broad gauge |
| colspan=4 style="text-align:left;" | Prototype narrow gauges | |||
| O21 | 21 mm | 3' | {{RailGauge|3ft}} |
| O16.5 | 16.5 mm (H0 gauge) | 2' 4¼" | 2' - 2'6" |
| O14 | 14 mm | 2' | {{RailGauge|2ft}} |
| O9 | 9 mm (N gauge) | 15½" | {{RailGauge|15in}} |