Cheonan's 2021 population is now estimated at 688,543. In 1950, the population of Cheonan was 21,851. Cheonan has grown by 8,741 since 2015, which represents a 1.29% annual change. These population estimates and projections come from the latest revision of the UN World Urbanization Prospects. These estimates represent the Urban agglomeration of Cheonan, which typically includes Cheonan's population in addition to adjacent suburban areas.