Calumet is a city in O'Brien County, Iowa, United States.

[4] According to the United States Census Bureau, the city has a total area of 0.27 square miles (0.70 km2), all land.

There were 73 housing units at an average density of 274.1 per square mile (105.8/km2).

There were 86 housing units at an average density of 318.5 per square mile (123.0/km2).

29.3% of all households were made up of individuals, and 12% had someone living alone who was 65 years of age or older.

The racial makeup of the city was 96.69% White, 0.55% African American, 0.55% Asian, and 2.21% from two or more races.

31.2% of all households were made up of individuals, and 18.2% had someone living alone who was 65 years of age or older.

About 2.0% of families and 8.5% of the population were below the poverty line, including 6.4% of those under the age of eighteen and 25.0% of those 65 or over.

Calumet is served by the South O'Brien Community School District.