The village of Lake Zurich boundary comes within 0.1 miles (0.16 km) of the southwest corner of the CDP.

According to the United States Census Bureau, the Forest Lake CDP has a total area of 0.42 square miles (1.1 km2), of which 0.35 square miles (0.9 km2) are land and 0.1 square miles (0.2 km2), or 14.86%, are water,[4] consisting of the community's namesake water body.

As of the census[9] of 2010, there were 1,659 people, 662 households, and 446 families residing in the CDP.

There were 662 housing units at an average density of 1,439.1 per square mile (555.6/km2).

14.2% of all households were made up of individuals, and 3.0% had someone living alone who was 65 years of age or older.