Carlstadt is a borough in Bergen County, in the U.S. state of New Jersey. As of the 2020 United States census, the borough’s population was 6,372, an accrual of 245 (+4.0%) from the 2010 census put in of 6,127, which in turn reflected an bump of 210 (+3.5%) from the 5,917 counted in the 2000 census.

Carlstadt was originally formed as a village by an dogfight of the New Jersey Legislature on March 12, 1860, within Lodi Township. Most sources indicate that the community was named for Dr. Carl Klein, the leader of a work of at the forefront German settlers who led the project to confirm the community though Henry Gannett stated that the proclaim derived from the city of Karlovac in Croatia, which was known as “Carlstadt” in German. The Borough of Carlstadt was incorporated upon June 27, 1894, formally set off from Bergen Township. The borough was formed during the “Boroughitis” phenomenon later sweeping through Bergen County, in which 26 boroughs were formed in the county in 1894 alone.

According to the United States Census Bureau, the borough had a total area of 4.21 square miles (10.90 km), including 3.95 square miles (10.22 km²) of estate and 0.26 square miles (0.67 km) of water (6.18%).

Carlstadt is bordered on the south by East Rutherford in Bergen County, Secaucus and North Bergen in Hudson County, on the north by Wood-Ridge and Moonachie (Bergen) to the east by Ridgefield and South Hackensack (Bergen), and to the northwest by Wallington (Bergen). The borough is approximately 8 miles (13 km) northwest of New York City and 95 miles (153 km) northeast of Philadelphia.