Odin Township (E½ T2N R1E) is centered at 38°36'N 89°4'W (38.364, -89.059). It is transversed east-west by U.S. Route 50. The city of Odin is located in the eastern part of the township. Prior to 1896 Odin Township included what is now Sandoval Township. According to the 2010 census, the township has a total area of 18.08 square miles (46.8 km2), of which 18.05 square miles (46.7 km2) (or 99.83%) is land and 0.02 square miles (0.052 km2) (or 0.11%) is water.