According to the United States Census Bureau, the township has a total area of 36.1 square miles (93 km2), all land.

Eldred Township is located in the southwestern part of Warren County in the Pittsburgh High Plateau.

Tributaries of Caldwell Creek in Eldred Township include West Branch Caldwell Creek and its tributaries, Three Bridges Run and Middle Branch.

The highest elevation is 1,882 ft (574 m) on a high point at the northeastern part of the township about 1 mile east-northeast of Sanford, Pennsylvania.

20.7% of all households were made up of individuals, and 7.7% had someone living alone who was 65 years of age or older.