Karatsu is a city located in Saga Prefecture on the island of Kyushu, Japan. Its name, formed from the Japanese word roots 唐 kara, and 津 tsu, signifies its historical importance as an ancient trading port between Japan with China and Korea. As of 1 June 2024, the city had an estimated population of 114,695 in 51375 households, and a population density of 200 persons per km2. The total area of the city is 487.60 km2.