Marnhull /ˈmɑːrnəl/ is a village and civil parish in the county of Dorset in southern England. It lies in the Blackmore Vale in the North Dorset administrative district, 3 miles (4.8 km) north of the small town of Sturminster Newton. The resort towns of Bournemouth and Weymouth are approximately 30 miles (48 km) to the south. Marnhull is sited on a low ridge of Corallian limestone above the valley of the River Stour, which forms the northern and western boundaries of the parish. In the 2011 census the parish had 962 dwellings, 905 households and a population of 1,998.