Kulm District is a district in the canton of Aargau, Switzerland. It is located west of Lake Hallwil and covers parts of the Wyna and Suhre valleys. The principal town is Unterkulm; the largest municipality is Reinach. The district contains 17 municipalities, is 101.35 km² in area and has a population of 39,323 (as of 31 December 2014).
Kulm district has an area, as of 2009, of 101.37 square kilometers (39.14 sq mi). Of this area, 50.46 km2 (19.48 sq mi) or 49.8% is used for agricultural purposes, while 32.21 km2 (12.44 sq mi) or 31.8% is forested. Of the rest of the land, 14.4 km2 (5.6 sq mi) or 14.2% is settled (buildings or roads).
The Kulm district has a population (as of December 2014) of 39,323.As of June 2009, 22.6% of the population are foreign nationals.
In 2000 there were 18,062 workers who lived in the municipality. Of these, 12,740 or about 70.5% of the residents worked outside the district while 7,159 people commuted into the district for work. There were a total of 12,481 jobs (of at least 6 hours per week) in the district.