Saint Charles Township is one of twelve townships in Floyd County, Iowa, USA.

As of the 2000 census, its population was 1,346.

[1] According to the United States Census Bureau, Saint Charles Township covers an area of 63.92 square miles (165.56 square kilometers); of this, 63.87 square miles (165.43 square kilometers, 99.92 percent) is land and 0.05 square miles (0.13 square kilometers, 0.08 percent) is water.

The city of Charles City is entirely within this township geographically but is a separate entity.