Cape gauge is 1067mm wide, because it is narrower than the standard gauge of 1435mm, so it is a kind of “narrow gauge”. It's named Cape Gauge because the former Cape Province of South Africa adopted this gauge in 1873. But the first country to install this gauge was Norway.

"Cape gauge" is actually a specific type of "narrow gauge." Any railway track with a width (gauge) smaller than the international standard of 1,435 mm (4 ft 821​ in) is classified as narrow gauge. Cape gauge specifically refers to a track width of 1,067 mm (3 ft 6 in). It was famously adopted by the Cape of Good Hope in South Africa in 1873 and subsequently became the standard for many countries, including Japan (except for Shinkansen), New Zealand, and parts of Australia and Southeast Asia. The broader category of Narrow gauge encompasses a variety of other widths, such as "Metre gauge" (1,000 mm) used in India and Europe, or even smaller "Bosnian gauge" (760 mm). The primary difference in application is that Cape gauge is robust enough to handle heavy, long-distance freight and passenger services at moderate speeds, whereas smaller narrow gauges are often restricted to industrial, mountainous, or light-commuter use. While standard gauge offers better stability for high-speed travel, Cape gauge is valued for being cheaper to construct in difficult, mountainous terrain.