Berlin is a city in Green Lake and Waushara Counties in the U.S. state of Wisconsin. The city is located mostly within the Town of Berlin in Green Lake County; only a small portion of the city extends into the Town of Aurora in Waushara County. According to the United States Census Bureau, the city has a total area of 6.3 square miles (16.3 sq. km), of which, 6.0 square miles (15.5 sq. km) of it is land and 0.3 square miles (0.9 sq. km) of it (5.23%) is water.