Hartola is a municipality of Finland. It is located in the Itä-Häme, Päijät-Häme region. The municipality has a population of 2,401 (31 December 2025), which make it the smallest municipality in Päijät-Häme in terms of population. It covers an area of 675.38 square kilometres (260.77 sq mi) of which 132.18 km2 (51.03 sq mi) is water. The population density is 4.42 inhabitants per square kilometre (11.4/sq mi). Neighbouring municipalities are Heinola, Joutsa, Luhanka, Pertunmaa and Sysmä.