Whately is located in Franklin County, Massachusetts. According to the United States Census Bureau, the population is 1,496 (2010 census) and has a total area of 20.7 square miles. Whately lies along the southern border of the county, north of Hampshire County, and is bordered by Conway to the northwest, Deerfield to the northeast, Sunderland to the east, Hatfield to the south, and Williamsburg to the west. Whately is located 11 miles south of Greenfield, 26 miles north of Springfield, and 95 miles west of Boston.
Whately lies along the western banks of the Connecticut River in the Pioneer Valley. The western part of town is hilly, with the highest point being the 980-foot (300 m) Mount Esther. East of the hills, the Mill River flows through town, with some swampland to the east between it and the Great Swamp Brook, a tributary which meets in the town. There is more marshy land in the southeast of town, closer to the Connecticut, and some small ponds between the two. Much of the land around the two rivers is cleared for farmland.