Kapilbastu district (Nepali: कपिलवस्तु जिल्ला) is one of the districts of Lumbini Province, Nepal. The district, with Kapilbastu municipality as its district headquarters, covers an area of 1,738 square kilometres (671 sq mi) and in 2001 had a population of 481,976, which increased to 571,936 in 2011 and later according 2021 census it further increased to 686,739.