Plainfield is located in Bremer county Iowa with a geographic area of 0.3 square miles. The total population in Plainfield is 405 with 48.6% male and 51.4% female. Children under age 5 represent 5.7% of the population, under age 18 equal 24.2% of the population and over age 65 is 15.3% of the population. The median household income is $59,250, per capita income is $29,709. There are a total of 172 housing units with 80.8% owner occupied. Education includes 52.9% of residents that are high school graduates and 7.6% with a bachelor's degree or higher. The average temperature in Plainfield in the summer is 72 degrees, and in the winter 23 degrees.