Duncombe is a city in Webster County, Iowa, United States.

[4] According to the United States Census Bureau, the city has a total area of 1.97 square miles (5.10 km2), all land.

There were 180 housing units at an average density of 91.7 per square mile (35.4/km2).

There were 193 housing units at an average density of 98.0 per square mile (37.8/km2).

The racial makeup of the city was 96.1% White, 0.5% African American, 0.7% Asian, and 2.7% from two or more races.

31.1% of all households were made up of individuals, and 15% had someone living alone who was 65 years of age or older.

There were 196 housing units at an average density of 99.6 per square mile (38.5/km2).

The racial makeup of the city was 98.31% White, 0.84% Native American, 0.21% Asian, and 0.63% from two or more races.

29.2% of all households were made up of individuals, and 15.1% had someone living alone who was 65 years of age or older.