page_title: OO gauge
hierarchical_section_title: OO gauge
caption_attribution_description: English: U.K. Prototype model of an 00 scale (1:76.2) shown with 5 pence coin for size, Photo by William J. Grimes.
context_page_description: OO gauge or OO scale is the most popular standard-gauge model railway standard in the United Kingdom despite being virtually unknown in other countries. This track gauge is one of several 4 mm-scale standards used, but it is the only one to be served by the major manufacturers. Unfortunately, the OO track gauge of 16.5 mm is actually incorrect for 4 mm scale, giving a track gauge equivalent of 4 ft 1½ in instead of 4 ft 8½ in. However, since the 1960s, other gauges in the same scale have arisen to reflect the desire of some modellers for greater scale accuracy.
context_section_description: OO gauge or OO scale (also spelled 00 gauge and 00 scale) is the most popular standard-gauge model railway standard in the United Kingdom despite being virtually unknown in other countries. This track gauge is one of several 4 mm-scale standards (4 mm to 1 foot, or 1:76.2) used, but it is the only one to be served by the major manufacturers. Unfortunately, the OO track gauge of 16.5 mm (0.65 in) (same as H0 scale) is actually incorrect for 4 mm scale, giving a track gauge equivalent of 4 ft 1½ in instead of 4 ft 8½ in. However, since the 1960s, other gauges in the same scale have arisen (18.2 mm or EM and 18.83 or Scalefour) to reflect the desire of some modellers for greater scale accuracy.
caption: U.K. prototype model of a 00 scale (1:76) British Rail Class 25 shown with five pence coin for scale
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