The population of the CDP was 371 at the 2020 census, out of a total of 1,708 people in the town.

It was formerly known by several other names, including "Batavia", "Osbornville", and "Windham Center".

Windham is located at 42°18′41″N 74°14′49″W / 42.31139°N 74.24694°W / 42.31139; -74.24694 (42.311591, -74.247116),[6] in the valley of the Batavia Kill, a westward-flowing tributary of Schoharie Creek and part of the Mohawk River watershed.

According to the United States Census Bureau, the Windham CDP has a total area of 1.9 square miles (4.9 km2), all land.

41.3% of all households were made up of individuals, and 19.2% had someone living alone who was 65 years of age or older.