Fairfield is located in Butler county Ohio with a geographic area of 20.8 square miles. The total population in Fairfield is 42,623 with 47.6% male and 52.4% female. Children under age 5 represent 6.6% of the population, under age 18 equal 21.7% of the population and over age 65 is 17.4% of the population. The median household income is $63,655, per capita income is $32,551. There are a total of 17,447 housing units with 62.5% owner occupied. Education includes 31.3% of residents that are high school graduates and 33.3% with a bachelor's degree or higher. The average temperature in Fairfield in the summer is 75 degrees, and in the winter 32 degrees.
