New Hartford is a city in Butler County, Iowa, United States. The population was 516 at the 2010 census.
New Hartford's longitude and latitude coordinates in decimal form are 42.567189, -92.621435.
According to the United States Census Bureau, the city has a total area of 0.50 square miles (1.29 km2), all land.
At the 2010 census, there were 516 people, 215 households and 147 families living in the city. The population density was 1,032.0 inhabitants per square mile (398.5/km2). There were 234 housing units at an average density of 468.0 per square mile (180.7/km2). The racial makeup of the city was 98.1% White, 0.4% Native American, 0.2% Asian, 0.4% from other races, and 1.0% from two or more races. Hispanic or Latino of any race were 1.6% of the population.
There were 215 households of which 30.7% had children under the age of 18 living with them, 53.5% were married couples living together, 10.7% had a female householder with no husband present, 4.2% had a male householder with no wife present, and 31.6% were non-families. 26.5% of all households were made up of individuals and 9.8% had someone living alone who was 65 years of age or older. The average household size was 2.40 and the average family size was 2.83.