The US gallon per hour is a unit of volumetric flow rate equal to one United States gallon passing a point every hour. Its symbol is gal US/h, commonly abbreviated GPH. At 3.785 litres to the gallon, an hour at this rate delivers a little under four litres, which places it among the slow, continuous flows of heating, irrigation and fuel systems.
Drip irrigation is its most familiar use in America. Emitters are sold rated at 0.5, 1 and 2 gallons per hour, and a garden bed is designed by choosing an emitter for each plant and multiplying by the number of plants. A zone of two hundred one-gallon emitters draws 200 gallons per hour, and a two-hour cycle applies 400 gallons — figures a homeowner can check against the water bill.
Oil burners are rated in it in the United States, exactly as in Britain. A residential oil furnace carries a nozzle marked 0.75 or 1.00 gallons per hour, and multiplying by about 140,000 British thermal units per gallon gives the burner's firing rate. The nozzle is thus both a fuel metering device and the effective rating plate of the appliance.
Water heaters and small appliances follow. A tankless water heater's recovery, an ice machine's water consumption, a humidifier's evaporation rate and a coffee urn's draw are all commonly expressed in gallons per hour, since these appliances run more or less continuously and are chosen to match a daily demand.
Fuel consumption of engines under steady load is quoted this way in American practice. A generator burns 0.5 to 3 gallons per hour depending on size and load, a boat's engine several, and a large marine diesel dozens. Dividing the tank capacity by the hourly rate gives the endurance, which for a boat is the number that actually matters.
For scale, one US gallon per hour is about 3.79 litres per hour, and 264 gallons per hour is about a cubic metre per hour. Sixty gallons per hour is one gallon per minute, so the two American flow units are connected by the same factor that connects the minute to the hour.
One US gallon per hour equals about 3.785 litres per hour, about 0.003785 cubic metres per hour, or about 0.8327 imperial gallons per hour.
| Unit | Symbol | 1 US Gallon per hour equals | 1 of these equals | Converter |
|---|---|---|---|---|
| Milliliter per second | mL/s | 1.05150327333 mL/s | 0.951019388489 gal US/h | US Gallons per hour to Milliliters per second |
| Milliliter per minute | mL/min | 63.0901964 mL/min | 0.0158503231415 gal US/h | US Gallons per hour to Milliliters per minute |
| Milliliter per hour | mL/h | 3785.411784 mL/h | 0.000264172052358 gal US/h | US Gallons per hour to Milliliters per hour |
| Liter per second | L/s | 0.00105150327333 L/s | 951.019388489 gal US/h | US Gallons per hour to Liters per second |
| Liter per minute | L/min | 0.0630901964 L/min | 15.8503231415 gal US/h | US Gallons per hour to Liters per minute |
| Liter per hour | L/hour | 3.785411784 L/hour | 0.264172052358 gal US/h | US Gallons per hour to Liters per hour |
| Cubic millimeter per second | mm³/s | 1051.50327333 mm³/s | 0.000951019388489 gal US/h | US Gallons per hour to Cubic millimeters per second |
| Cubic millimeter per minute | mm³/min | 63090.1964 mm³/min | 0.0000158503231415 gal US/h | US Gallons per hour to Cubic millimeters per minute |
| Cubic millimeter per hour | mm³/hour | 3785411.784 mm³/hour | 0.000000264172052358 gal US/h | US Gallons per hour to Cubic millimeters per hour |
| Cubic centimeter per second | cm³/s | 1.05150327333 cm³/s | 0.951019388489 gal US/h | US Gallons per hour to Cubic centimeters per second |
| Cubic centimeter per minute | cm³/min | 63.0901964 cm³/min | 0.0158503231415 gal US/h | US Gallons per hour to Cubic centimeters per minute |
| Cubic centimeter per hour | cm³/h | 3785.411784 cm³/h | 0.000264172052358 gal US/h | US Gallons per hour to Cubic centimeters per hour |
| Cubic meter per second | m³/s | 0.00000105150327333 m³/s | 951019.388489 gal US/h | US Gallons per hour to Cubic meters per second |
| Cubic meter per minute | m³/min | 0.0000630901964 m³/min | 15850.3231415 gal US/h | US Gallons per hour to Cubic meters per minute |
| Cubic meter per hour | m³/h | 0.003785411784 m³/h | 264.172052358 gal US/h | US Gallons per hour to Cubic meters per hour |
| Cubic inch per second | in³/s | 0.0641666666667 in³/s | 15.5844155844 gal US/h | US Gallons per hour to Cubic inches per second |
| Cubic inch per minute | in³/min | 3.85 in³/min | 0.25974025974 gal US/h | US Gallons per hour to Cubic inches per minute |
| Cubic inch per hour | in³/h | 231 in³/h | 0.004329004329 gal US/h | US Gallons per hour to Cubic inches per hour |
| Cubic foot per second | ft³/s | 0.0000371334876569 ft³/s | 26929.870128 gal US/h | US Gallons per hour to Cubic feet per second |
| Cubic foot per minute | ft³/min | 0.00222800925942 ft³/min | 448.831168799 gal US/h | US Gallons per hour to Cubic feet per minute |
| Cubic foot per hour | ft³/h | 0.133680555565 ft³/h | 7.48051947999 gal US/h | US Gallons per hour to Cubic feet per hour |
| Fluid ounce per second | fl oz/s | 0.0370077415391 fl oz/s | 27.0213733239 gal US/h | US Gallons per hour to Fluid ounces per second |
| Fluid ounce per minute | fl oz/min | 2.22046449234 fl oz/min | 0.450356222064 gal US/h | US Gallons per hour to Fluid ounces per minute |
| Fluid ounce per hour | fl oz/h | 133.227869541 fl oz/h | 0.00750593703441 gal US/h | US Gallons per hour to Fluid ounces per hour |
| Gallon per second | gal/s | 0.000231298384619 gal/s | 4323.41973182 gal US/h | US Gallons per hour to Gallons per second |
| Gallon per minute | gal/min | 0.0138779030771 gal/min | 72.0569955303 gal US/h | US Gallons per hour to Gallons per minute |
| Gallon per hour | gal/h | 0.832674184629 gal/h | 1.2009499255 gal US/h | US Gallons per hour to Gallons per hour |
| US Gallon per second | gal US/s | 0.000277777777778 gal US/s | 3600 gal US/h | US Gallons per hour to US Gallons per second |
| US Gallon per minute | gal US/min | 0.0166666666667 gal US/min | 60 gal US/h | US Gallons per hour to US Gallons per minute |