Acre-Inch

An acre-inch is a unit of water volume commonly used in irrigation planning, representing the amount of water required to cover one acre to a uniform depth of one inch. This equals approximately 27,154 U.S. gallons or 3,630 cubic feet. Irrigation systems are rated by how many acre-inches they can deliver per hour, and crop water requirements are often stated in inches per week. For example, corn at peak water demand may need 0.30–0.35 inches per day, which translates to roughly 8,100–9,500 gallons per acre per day. Understanding acre-inch measurements is essential for sizing irrigation equipment, estimating pumping costs, and managing water rights.