Lewis Township is bordered by Cogan House Township to the west, McIntyre Township to the north, Cascade Township to the east, Gamble Township to the southeast, Hepburn Township borders at the extreme southeast corner of Lewis Township, and by Lycoming Township to the south [REF].
According to the United States Census Bureau, the township has a total area of 37.8 square miles (98.0 km2), all of it land.