Bancroft is a city in the Gem Valley of Caribou County, Idaho, United States. The population was 382 at the 2000 census.
Bancroft is located at 42°43′10″N 111°53′10″W / 42.71944°N 111.88611°W / 42.71944; -111.88611 (42.719440, -111.886194), in the Portneuf Valley. It is a railroad town and lies on the historic route of old U.S. Highway 30. The elevation is 5,420 feet (1,650 m).
According to the United States Census Bureau, the city has a total area of 0.7 square miles (1.7 km²), all of it land.