Most railways in Europe use the standard gauge of 1,435 mm (4 ft 8+1⁄2 in). Some countries use broad gauge, of which there are three types. Narrow gauges are also in use.

• Russian gauge
  • 1,520 mm (4 ft 11+27⁄32 in): former Soviet Union states
  • 1,524 mm (5 ft): Finland and Estonia

  (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.)

• Irish gauge
  • 1,600 mm (5 ft 3 in): Republic of Ireland and Northern Ireland
• Iberian gauge
  • 1,668 mm (5 ft 5+21⁄32 in): Portugal and Spain

Apart from Russia and Finland, all high-speed rail in Europe uses standard-gauge (1,435 mm (4 ft 8+1⁄2 in)) tracks.

• Rail gauge in North America
• Rail gauge in South America
• Rail gauge in Australia