Stephenville is located in Erath county Texas with a geographic area of 11.9 square miles. The total population in Stephenville is 20,887 with 46.2% male and 53.8% female. Children under age 5 represent 5.2% of the population, under age 18 equal 19.4% of the population and over age 65 is 11.5% of the population. The median household income is $48,602, per capita income is $25,189. There are a total of 7,291 housing units with 45.9% owner occupied. Education includes 18.9% of residents that are high school graduates and 34.9% with a bachelor's degree or higher. The average temperature in Stephenville in the summer is 81 degrees, and in the winter 49 degrees.