 According to the United States Census Bureau, the township has a total area of , all of it land.Farmington Township is bordered by Osceola Township to the west and north, Nelson Township to the north, Lawrence Township to the east and north, Tioga Township to the east, Middlebury Township to the south and Chatham and Deerfield Townships to the west.As of the census of 2000, there were 636 people, 238 households, and 183 families residing in the township.