Editing OO gauge (section)

{{Short description|Model railroad gauge}}
{{redirect|00 gauge|the wire gauge|American wire gauge}}
{{more citations needed|date=May 2025}}
{{Infobox Model Rail Scale
| name = OO gauge
| image_filename = OO Scale BR 25054.JPG
| image_caption = UK prototype model of a OO scale (1:76) [[British Rail Class 25]] shown with a [[Five pence (British coin)|five pence coin]] for scale
| widthpx = 
| scale = 4 mm to 1 ft
| ratio = 1:76.2
| gauge = {{RailGauge|16.5 mm}}
| prototype_gauge = [[Standard gauge]]
}}
'''OO gauge''' or '''OO scale''' (also, '''00 gauge''' and '''00 scale''') is the most popular [[Standard-gauge railway|standard gauge]] [[model railway]] standard in the United Kingdom,<ref>{{Cite web |title=OO - World Of Railways |url=https://www.world-of-railways.co.uk/Model-Railways/OO |access-date=2022-03-31 |website=www.world-of-railways.co.uk}}</ref> outside of which it is virtually unknown. OO gauge is one of several [[4 mm scale|4 mm-scale]] standards (4&nbsp;mm to {{convert|1|ft|mm|1|abbr=on|order=out}}, or 1:76.2), and the only one to be marketed by major manufacturers. The OO track gauge of {{RailGauge|16.5 mm}} (same as the 1:87 [[HO scale]]) corresponds to prototypical gauge of {{nowrap|4 ft {{frac|1|1|2}} in}}, rather than {{nowrap|4 ft {{frac|8|1|2}} in}} standard gauge.<ref>{{Cite web |title=Model Railway Basics - What's the difference between OO and HO scale or gauge? |url=https://www.scalemodelscenery.co.uk/blogs/whats-the-difference-between-oo-and-ho-scale-or-gauge |access-date=2024-12-29 |website=Scale Model Scenery |language=en-GB}}</ref> However, since the 1960s, other gauges in the same scale have arisen—18.2&nbsp;mm ([[EM gauge|EM]]) and 18.83&nbsp;mm ([[Protofour|Scalefour]])—to reflect the desire of some modellers for greater scale accuracy.