The vast majority of Finnish narrow-gauge railways were owned and operated by private companies. There are only a few instances where narrow-gauge railways were in direct connection with each other, and those interchanges did not last for long. The railways never formed a regional rail traffic network, but were only focused on maintaining connections between the national Russian-gauge railway network and the off-line industries.
Some railways were closed due to competition from the roads, others were converted to Russian gauge.
Common carriers
The Lovisa–Wesijärvi railway (1900–1960) that operated an line between Lahti and Loviisa. The Hyvinkää–Karkkila railway that operated a line The Jokioinen Railway that operated a line until 1974, being the last common-carrier narrow-gauge railway in Finland.
Other lines were notably shorter. The common gauges were and , with a few railways built with and gauges.
Tourist and heritage lines
Narrow-gauge tourist and heritage lines of gauge and narrow gauge still operate. Jokioinen Museum Railway, , 14 km, Jokioinen–Minkio–Humpilla. Nykarleby Jernväg, , 2 km. Tankavaara Kultakylä, , opened in 1997. Outokummun Kaivosrautatie, , 1.15 km, former copper mine.