A cubic inch is the volume of a cube which is one inch long on each edge. It is equal to 16.387064 cm³.
Historically, internal combustion engines produced in the United States had their engine displacements stated in cubic inches. In the case of automobile engines, this ceased by the 1980s, after which displacements have been stated in litres. The terminology continues to be used for older vehicles. The United Kingdom, however, used litres or cubic centimetres almost exclusively from the beginning, which was perhaps indicative of the British car industry's continental ties and sales aspirations.