Izmit's 2025 population is now estimated at 376,464. In 1950, the population of Izmit was 57,276. Izmit has grown by 4,986 in the last year, which represents a 1.34% 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 Izmit, which typically includes Izmit's population in addition to adjacent suburban areas.