Plainfield is a city in Bremer County, Iowa, United States.

[5] According to the United States Census Bureau, the city has a total area of 0.33 square miles (0.85 km2), all land.

There were 189 housing units at an average density of 564.2 per square mile (217.8/km2).

There were 197 housing units at an average density of 597.0 per square mile (230.5/km2).

28.1% of all households were made up of individuals, and 11.8% had someone living alone who was 65 years of age or older.

There were 202 housing units at an average density of 621.4 per square mile (239.9/km2).

The racial makeup of the city was 99.54% White, 0.23% Native American, and 0.23% from two or more races.

30.9% of all households were made up of individuals, and 16.5% had someone living alone who was 65 years of age or older.

[11] It was established on July 1, 1997 by the merger of the Nashua and Plainfield school districts.