Rail gauge is the distance from the inside of one rail on a railroad track to the inside of the other. Most countries use a standard gauge of 1,435 mm (4 ft, 8 1/2 in). Wider gauges are called broad gauge, smaller gauges are called narrow gauge. Broad gauge is usually used where the track needs to have heavy things moving on it. Narrow gauge is used to build railroads for less money, because the smaller track costs less. Places where different gauges meet are called break of gauge.