A cubic inch (in³) is a unit of volume in the Imperial and U.S. customary systems. It is defined as the volume of a cube with sides measuring one inch. The exact, canonical definition is 1 in³ = 16.387 cm³.
The cubic inch has roots in the British Imperial system, established in 1824. It became standard in the U.S. following the adoption of the Imperial system. The unit has been used consistently in engineering and manufacturing, especially in the automotive industry.
Cubic inches are commonly used in the U.S. for measuring engine displacement, appliance capacities, and container volumes. In everyday life, it may apply to packaging dimensions and storage capacities. This unit is primarily used in the United States and a few other countries that follow the Imperial system.