Portesham, sometimes also spelled Portisham, is a village and civil parish in the county of Dorset in southwest England, situated in the West Dorset administrative district approximately 6 miles (10 km) northwest of Weymouth, 6 miles (10 km) southwest of the county town Dorchester, and 2 miles (3 km) northeast of the Jurassic Coast World Heritage Site at Chesil Beach. The parish is quite large, covering several outlying hamlets and what were once their manors. In the 2011 census it had a population of 685 in 316 households and 342 dwellings.