Custer is located near the geographic center of Mason County in west Michigan. At the time of the 2010 census, the population of Custer was 284. There were 110 households of which 30.9% had children under the age of 18 living with them, 44.5% were married couples living together; 12.7% had a female householder with no husband present, 8.2% had a male householder with no wife present, and 34.5% were non-families. 26.4% of all households were made up of individuals and 7.3% had someone living alone who was 65 years of age or older. The average household size was 2.58 and the average family size was 3.06.
The median age in the village in 2010 was 39 years. 23.6% of residents were under the age of 18; 10.9% were between the ages of 18 and 24; 20.7% were from 25 to 44; 28.1% were from 45 to 64; and 16.5% were 65 years of age or older. The gender makeup of the village was 51.4% male and 48.6% female.