Frankfort is located in Will county Illinois with a geographic area of 15.8 square miles. The total population in Frankfort is 19,166 with 49.1% male and 50.9% female. Children under age 5 represent 4.3% of the population, under age 18 equal 29.7% of the population and over age 65 is 16.3% of the population. The median household income is $140,731, per capita income is $51,278. There are a total of 6,072 housing units with 94.8% owner occupied. Education includes 14.1% of residents that are high school graduates and 62.7% with a bachelor's degree or higher. The average temperature in Frankfort in the summer is 74 degrees, and in the winter 27 degrees.