|terrain = [[Region:Lounais-Suomi|Lounais-Suomi]]

'''Kustavi''' (Swedish: Gustavs) is a municipality in the region of [[Region:Lounais-Suomi|Lounais-Suomi]] in [[Country:Finland|Finland]]. It is in the province of [https://en.wikipedia.org/wiki/Western_Finland_Province Western Finland] and is part of the Southwest Finland region. The municipality has a population of 924 (31 January 2019) and covers an area of 770.15 square kilometres (297.36 sq mi) of which 603.45 km2 (232.99 sq mi) is water. The population density is 5.55 inhabitants per square kilometre (14.4/sq mi).