According to the United States Census Bureau, the town has a total area of 16.3 square miles (42 km2), of which 0.1 sq mi (0.26 km2) is water, comprising 0.37% of the town. Drained by the Cold River, Langdon lies within the Connecticut River watershed.[1] The highest point in town is the summit of Holden Hill, at 1,348 feet (411 m) above sea level.