Hartwick is located in Poweshiek county Iowa with a geographic area of 0.2 square miles. The total population in Hartwick is 131 with 34.4% male and 65.6% female. Children under age 5 represent 22.1% of the population, under age 18 equal 44.3% of the population and over age 65 is 12.2% of the population. The median household income is $67,500, per capita income is $21,558. There are a total of 42 housing units with 83.3% owner occupied. Education includes 45.2% of residents that are high school graduates and 19.0% with a bachelor's degree or higher. The average temperature in Hartwick in the summer is 72 degrees, and in the winter 23 degrees.