Most railways in Europe use the standard gauge of . Some countries use broad gauge, of which there are three types. Narrow gauges are also in use.
former Soviet Union states
(The difference is within tolerance limits, so it is possible to exchange trains between 1520 mm and 1524 mm networks without changes to the wheelsets, however sometimes issues like stuck rolling stock might occur.)
Republic of Ireland and Northern Ireland
Portugal and Spain
See main article: Narrow-gauge railways in Europe.
Apart from Russia and Finland, all high-speed rail in Europe uses standard-gauge tracks.