Plain city is located in Madison county Ohio with a geographic area of 2.5 square miles. The total population in Plain city is 3,831 with 50.9% male and 49.1% female. Children under age 5 represent 8.6% of the population, under age 18 equal 28.2% of the population and over age 65 is 20.1% of the population. The median household income is $77,448, per capita income is $33,143. There are a total of 1,463 housing units with 72.5% owner occupied. Education includes 30.6% of residents that are high school graduates and 30.6% with a bachelor's degree or higher. The average temperature in Plain city in the summer is 73 degrees, and in the winter 32 degrees.