what scale is oo gauge

OO gauge or OO scale is a popular standard gauge model railway standard in the United Kingdom. It is one of several 4 mm-scale standards, and the only one to be marketed by major manufacturers. The OO track gauge of 16.5 mm (0.65 in) corresponds to a scale ratio of 1:76.2 or 4 mm to 1 ft. Therefore, one foot (12 inches) in the real world is equal to 4mm (or 0.16 inches) in OO gauge. The prototype gauge for OO gauge is the standard gauge, which is 4 ft 8+1⁄2 in. The name OO gauge comes from the fact that it was originally called "double-O" because it was twice the size of the then-popular 00 gauge. In summary, OO gauge has a scale ratio of 1:76.2 or 4 mm to 1 ft, and a track gauge of 16.5 mm (0.65 in) .