1 Gallon [Fluid, US] = 231 Cubic Inches
1 Gallon [Dry, US] = 268.802501 Cubic Inches
1 Gallon [UK] = 277.419432 Cubic Inches
Gallon is an imperial and US Customary unit. There is one type of gallon in imperial system and 2 types (liquid and dry) in US Customary system. The abbreviation is "gal".
Cubic Inch is an imperial and US Customary volume unit. It is defined as a cube with all sides are one inch in length. The abbreviation is "in3".