[2] Clay Township is located in north-central Butler County and contains the unincorporated communities of Claytonia, Sherwin, Euclid, Muddy Creek, and Queen Junction.

It surrounds the borough of West Sunbury but is a separate entity.

According to the United States Census Bureau, the township has a total area of 25.1 square miles (65.0 km2), all land.

There were 1,036 housing units at an average density of 41.2 per square mile (15.9/km2).

19.4% of all households were made up of individuals, and 6.7% had someone living alone who was 65 years of age or older.