Alma Township is located in Marion County, Illinois. As of the 2010 census, its population was 836 and it contained 374 housing units.
Alma Township (T3N R3E) is centered at 38ð41'N 88ð52'W (38.689, -88.865). According to the 2010 census, the township has a total area of , of which (or 99.81%) is land and (or 0.19%) is water.