Chahardangeh District () is in Sari County, Mazandaran province, Iran. Its capital is the city of Kiasar.
At the time of the 2006 National Census, the district's population was 19,969 in 5,149 households. The following census in 2011 counted 15,796 people in 4,871 households. The 2016 census measured the population of the district as 17,376 inhabitants in 6,035 households.