The Municipality of Lebak is a coastal municipality in the province of Sultan Kudarat, Philippines. According to the 2015 census, it has a population of 88,868 people. The municipality of Lebak lies in the northernmost part of the coastal area of Sultan Kudarat, about 168 kilometres from Isulan, the capital town of Sultan Kudarat. ^ Census of Population. "Region XII ". Total Population by Province, City, Municipality and Barangay. PSA. Retrieved 20 June 2016.