According to the 2021 census gazetteer files, Buck Township has a total area of 34.27 square miles (88.76 km2), all land.

[3] As of the 2020 census[2] there were 214 people, 127 households, and 86 families residing in the township.

There were 124 housing units at an average density of 3.62 per square mile (1.40/km2).

The racial makeup of the township was 98.13% White, 0.00% African American, 0.00% Native American, 0.00% Asian, 0.00% Pacific Islander, 0.00% from other races, and 1.87% from two or more races.

21.30% of all households were made up of individuals, and 7.10% had someone living alone who was 65 years of age or older.