Hartwick is a city in Poweshiek County, Iowa, United States.

[3] According to the United States Census Bureau, the city has a total area of 0.13 square miles (0.34 km2), all land.

There were 39 housing units at an average density of 246.7 per square mile (95.2/km2).

There were 40 housing units at an average density of 307.7 per square mile (118.8/km2).

28.9% of all households were made up of individuals, and 10.5% had someone living alone who was 65 years of age or older.

There were 40 housing units at an average density of 308.8 per square mile (119.2/km2).

27.8% of all households were made up of individuals, and 19.4% had someone living alone who was 65 years of age or older.

There were no families and 2.7% of the population living below the poverty line, including no under eighteens and none of those over 64.