Grant Township is one of fifteen townships in DeKalb County, Indiana. As of the 2020 census, its population was 3,086, down from 3,245 at the 2010 census, and it contained 1,293 housing units.
According to the 2010 census, the township has a total area of , of which (or 99.89%) is land and (or 0.11%) is water.
The township contains three cemeteries: Lutz, Ridge, and Tamarack.
Grant Township residents are eligible to obtain a library card at the Waterloo-Grant Township Public Library in Waterloo.