Hardin is a village in Calhoun County, Illinois, United States. The population was 959 at the 2000 census. It is the county seat of Calhoun County.
Hardin is located at 39°9′30″N 90°37′6″W / 39.15833°N 90.61833°W / 39.15833; -90.61833 (39.158271, -90.618239).
According to the United States Census Bureau, the village has a total area of 2.3 square miles (5.9 km²), of which, 2.1 square miles (5.4 km²) of it is land and 0.2 square miles (0.5 km²) of it (7.89%) is water.