Lusby is an unincorporated community and census-designated place (CDP) in Calvert County, Maryland, United States. The population of the CDP was 1,835 at the 2010 census. Lusby is located near the southern end of Calvert County at 38°21′13″N 76°26′12″W (38.353555, -76.436615). It is bordered to the southwest by Solomons, a tourist resort town, to the south by Drum Point (across tidal Mill Creek), and to the southeast by Chesapeake Ranch Estates, a large community governed by a homeowners' association. According to the United States Census Bureau, the Lusby CDP has a total area of 3.7 square miles (9.5 km2), of which 3.5 square miles (9.1 km2) is land and 0.15 square miles (0.4 km2), or 4.51%, is water.