Vehmaa is a 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 2,268 and covers an area of 202.09 square kilometres (78.03 sq mi) of which 13.32 km2 (5.14 sq mi) is water. The population density is 12.01 inhabitants per square kilometre (31.1/sq mi).