The Town of Forssa engages in twin town activities with the following towns:

(Year of becoming twin towns)

Flag of Hungary 
Gödöllö is located in Hungary, approximately 30 km east of Budapest.
It has approximately 34,000 residents. (1990)

Flag of Norway 
Sarpsborg is located in Norway, by the Sarpfossen rapids around 80 km south of Oslo. It has approximately 57,000 residents. (1951)

Flag of Canada 
Sault Ste. Marie is located in the state of Ontario by the Great Lakes in the border of the United States and Canada. It has approximately 75,000 residents. (1990)

Flag of Russia 
Serpukhov is located in Russia in a bend of the Nara and Serpeika Rivers approximately 100 km south from Moscow. It has approximately 150,000 residents. (1964)

Flag of Danmark 
Struer is located in Jutland, Denmark, on the southern coast of the Limfjord. It has approximately 21,000 residents. (1951)

Flag of Sweden 
Södertälje is located in Sweden by the shores of Lake Mälaren around 30 km south of Stockholm. It has approximately 98,000 residents. (1946)

Flag of Sweden 
Tierp is located north of Uppsala, Sweden. It has approximately 21,000 residents. (1969)