As of 1 October 2019, the city had an estimated population of 386,999 in 164,087 households, and a population density of 999 persons per km². The total area of the city was 387.20 km2 (149.50 sq mi).
Okazaki is in the coastal plains of southeastern Aichi Prefecture. The ground rises to undulating hills in the former Nukata area to the northeast. About 60 percent of the city area is forested and remains sparsely populated.
Okazaki is about 250 miles (400 km) from Tokyo, to the southwest.