Kalundborg Municipality is a kommune in the Region Sjælland on the west coast of the island of Zealand in Denmark. The municipality covers an area of 604 km2 (233 sq mi), and has a total population of 48,602. Its mayor is Martin Damm, a member of Venstre. The main town and the site of its municipal council is the city of Kalundborg.

Zealand at 7,031 km2 is the largest and most populous island in Denmark proper. Zealand had a population of 2,319,705 on 1 January 2020, comprising 40% of the country's population.