Oita's 2025 population is now estimated at 474,415. In 1950, the population of Oita was 81,791. Oita experienced a decrease of -1,057 residents over the past year, marking an annual decline of -0.22%.These population estimates and projections come from the latest revision of the UN World Urbanization Prospects. These estimates represent the Urban agglomeration of Oita, which typically includes Oita's population in addition to adjacent suburban areas.