gph

GPH stands for gallons per hour, a unit of flow rate used to describe the volume of liquid that passes through a device or system in one hour. It is commonly used in the United States for equipment such as water pumps, irrigation controllers, fuel transfer systems, and beverage dispensers. GPH remains prevalent in consumer and industrial specifications due to historical usage and familiarity with the gallon as a unit of volume.

One GPH equals 3.78541 liters per hour for US gallons. In terms of per-minute rate, 1 GPH is about 0.0631 L/min. Some markets refer to Imperial gallons; in that case, 1 GPH equals 4.54609 L/hour, about 0.0758 L/min, but many manufacturers specify gph using US gallons by default, so users should check product documents.

Common pump and equipment ratings span from a few tens of gph in small, hobbyist devices to thousands of gph in larger pumps. The actual delivered flow depends on head pressure, pipe diameter, viscosity of the liquid, and pump design.

GPH is related to gallons per minute (GPM); the relationship is GPM = GPH ÷ 60, and GPH = GPM × 60. When precision matters, many specifications also state the corresponding liters per hour (LPH) or use the metric unit L/h.