Chapin is a village in Morgan County, Illinois, United States. The population was 592 at the 2000 census. It is part of the Jacksonville Micropolitan Statistical Area.
Chapin is located at 39°46′3″N 90°24′7″W / 39.7675°N 90.40194°W / 39.7675; -90.40194 (39.767407, -90.401844).
According to the United States Census Bureau, the village has a total area of 1.0 square miles (2.5 km²), all of it land.