Loimaa (Finnish: [ˈloi̯mɑː]; historical Swedish: Loimijoki) is a town and municipality of Finland.
It is located in the province of Western Finland and is part of the Southwest Finland region. The municipality has a population of 15,333 (31 October 2024) and covers an area of 851.93 square kilometers (328.93 sq mi) of which 3.96 km2 (1.53 sq mi) is water. The population density is 18.08 inhabitants per square kilometer (46.8/sq mi).
Loimaa's neighboring municipalities are Huittinen, Humppila, Koski Tl, Marttila, Oripää, Punkalaidun, Pöytyä, Somero, Säkylä and Ypäjä.