Forssa is a city in southwestern Häme, Finland, located in the western part of Kanta-Häme province. The city is the center of the Forssa region.

Of the three cities in Kanta-Häme, Forssa is the smallest with about 16,900 inhabitants. Among Finnish municipalities, Forssa is the 67th largest in terms of population. The population is concentrated in the central part of Forssa, located in the southern part of the city's administrative area, and in the northern parts there are fewer rural settlements in the area of ​​the former Koijärvi municipality.

Forssa covers an area of ​​253.38 square kilometers and has an average population density of about 68 inhabitants per square kilometer. The share of water bodies in the area is small, but an important element in the cityscape is the Loimijoki, at the beginning of which the city is located. Other significant water bodies are Kaukjärvi, partly located in Forssa, and Koijärvi, known as the birthplace of the green movement.

The neighboring municipalities of Forssa are Jokioinen in the west, Tammela in the east and south, Humppila and Urjala in the north. In addition to the city of Forssa, the Forssa region includes Jokioinen, Tammela, Humppila and Ypäjä. In addition to the above-mentioned municipalities, Somero and Urjala are also included in the Southwest Häme region. Forssa's location in the middle of the Helsinki – Turku – Tampere triangle is sometimes considered ideal, as business trips to the country's largest cities are fast. The distance to Helsinki is 110, to Tampere 87 and to Turku 88 kilometers.

Forssa grew and developed in the 19th century with the growth of the textile industry. In the mid-20th century, the city grew hardly at all between the world wars. A new period of growth began in the 1960s, driven by the construction industry. Since then, the city’s growth has stalled as industry has begun to downsize. Today, the food industry is a major employer.

Forssa had its largest population in the mid-1980s, when the city had just over 20,000 inhabitants for two years. By 1994, the population had declined by a few hundred, but since then the population decline had accelerated. By the end of 2005, Forssa had lost more than 2,000 inhabitants compared to the peak years. In 2008, the city’s population grew for the first time since 1993. Since 2010, the population has declined again, reaching about 17,300 in 2016.