Round Lake is a northern suburb of Chicago in Lake County, Illinois, United States. As of the 2010 census, it had a population of 18,289.
Round Lake is located at 42°21′15″N 88°6′2″W (42.354045, -88.100529).
According to the 2010 census, Round Lake has a total area of 5.635 square miles (14.59 km2), of which 5.47 square miles (14.17 km2) (or 97.07%) is land and 0.165 square miles (0.43 km2) (or 2.93%) is water.
As of 2010 United States Census, there were 18,289 people, 6,206 households, and 5,847 families residing in the village. The population increased 310% from the 2000 US Census total of 5,492. The population density is 3,225.6 people per square mile (1,244.9/km²). There are 6,206 housing units at an average density of 1,094.5 per square mile (422.5/km²). The racial makeup of the village is 68.9% White, 4.77% African American, 0.5% Native American, 12.7% Asian, 0.07% Pacific Islander, 9.69% from other races, and 3.24% from two or more races. 25.3% of the population are Hispanic or Latino of any race.
There 6,206 total housing units, of which 94.2% or (5,847) are occupied households. Of these occupied households 48% have children under the age of 18 living with them. 49.5% of the population was male, 50.5% female.