Begusarai's 2025 population is now estimated at 586,584. In 1950, the population of Begusarai was 14,973. Begusarai has grown by 20,184 in the last year, which represents a 3.56% 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 Begusarai, which typically includes Begusarai's population in addition to adjacent suburban areas.