>>1393283Hello newfriend and welcome to /n/.
55% of railways worldwide use the "standard gauge" of 1435 millimeters. This includes most of Europe, GB, the US, and many other countries around the world.
Smaller gauges include 1000mm and 1067mm which is mostly used by tram networks and tertiary railways, but also by some mainline railways.
Then there are the broad gauges of the ex-USSR and adjacent countries (1520mm), Irish gauge (1600mm) Iberian gauge (1668mm) and finally Indian gauge at 1676mm. It's the broadest "width" in wide use and is common in India, Sri Lanka, Pakistan and San Francisco's BART for some reason.
