Charlestown is located in Sullivan county New hampshire with a geographic area of 1.0 square miles. The total population in Charlestown is 933 with 55.7% male and 44.3% female. Children under age 5 represent 4.2% of the population, under age 18 equal 23.5% of the population and over age 65 is 19.9% of the population. The median household income is $72,540, per capita income is $26,396. There are a total of 449 housing units with 53.0% owner occupied. Education includes 45.7% of residents that are high school graduates and 13.8% with a bachelor's degree or higher. The average temperature in Charlestown in the summer is 68 degrees, and in the winter 23 degrees.