Tuusula is a municipality located in the southern interior of Finland within the Uusimaa region. It sits in the center of the Uusimaa region and is part of the Helsinki metropolitan area, which has a total population of approximately 1.62 million inhabitants.
The municipality has a population of approximately 42,000 people. It ranks as the 27th most populous municipality in Finland and is noted as the second most populous municipality without city status in the country, following Nurmijärvi.