Tuusula, lying on the shores of Tuusulanjärvi lake, is located in the province of Southern Finland and is part of the Uusimaa region. It covers an area of 225.46 square kilometres (87.05 sq mi) of which 5.95 km2 (2.30 sq mi) is water. The population density is 172.22 inhabitants per square kilometre (446.0 /sq mi).
Tuusula has three population centers. The administrative center is Hyrylä (about 19,500 residents), other two are Jokela (5,300 residents) and Kellokoski (4,300 residents). The remaining 4,400 residents are distributed to the rural areas outside of municipal centers.
The neighboring communes are Vantaa to the south, Nurmijärvi to the west, Hyvinkää to the north, Mäntsälä and Järvenpää to the north east, and Sipoo and Kerava to the east
