Saga is the capital city of Saga Prefecture, located on the island of Kyushu, Japan. Saga was the capital of Saga Domain in the Edo period, and the largest city of former Hizen Province. As of August 1, 2020, the city had an estimated population of 232,736 and a population density of 539 persons per km². The total area is 431.84 km².
Saga is located in the southeast part of Saga Prefecture. After the 2005 merger the city became very long north to south, bordering the Ariake Sea to the south and Fukuoka Prefecture to the southeast and north. The northern half of the city contains the Sefuri Mountains. Saga can also be regarded as within the Greater Fukuoka metropolitan area, and by extension, Fukuoka-Kitakyushu Metropolitan Area.