In process engineering, fluid transport is quantified by volumetric flow rate. The US Gallon per minute (GPM) is the standard unit for liquid flow in North American industrial and residential plumbing systems, while the Cubic meter per hour (m³/h) is the SI-derived unit preferred in international engineering and large-scale utility management.
GPM (US): Commonly used for pump sizing, fire sprinkler systems, and residential water meters. It represents the volume of one US liquid gallon passing a point in one minute.
m³/h: The standard for municipal water treatment, HVAC chilled water loops, and large-scale chemical processing. It represents the volume of a cube with one-meter sides passing a point in one hour.
To convert between these units, we utilize the relationship \(1 \text{ GPM} \approx 0.22712470704 \text{ m}^3/\text{h}\). This conversion is essential when integrating US-manufactured equipment into international process plants.
Gallon per minute (US) to Cubic meter per hour Conversion Reference Table
Gallon per minute (US) (GPM)
Cubic meter per hour (m³/h)
0.1
0.0227
0.5
0.1136
1.0
0.2271
2.0
0.4542
5.0
1.1356
10.0
2.2712
20.0
4.5425
50.0
11.3562
100.0
22.7125
500.0
113.5624
1000.0
227.1247
Conversion Example: 10 GPM to m³/h
To convert a flow rate of 10 GPM to m³/h, multiply the value by the conversion factor of 0.22712470704:
This factor is derived from the exact definition of a US liquid gallon (231 cubic inches) and the conversion of inches to meters. Since 1 gallon is exactly 0.003785411784 cubic meters, and there are 60 minutes in an hour, the calculation is 0.003785411784 multiplied by 60.
No. The US gallon is defined as 3.785 liters, whereas the Imperial (UK) gallon is approximately 4.546 liters. Always verify if your equipment specifications refer to US GPM or Imperial GPM to avoid significant flow rate errors.
"On fait la science avec des faits, comme on fait une maison avec des pierres ; mais une accumulation de faits n'est pas plus une science qu'un tas de pierres n'est une maison." "Science is built up of facts, as a house is built of stones; but an accumulation of facts is no more a science than a heap of stones is a house." — Henri Poincaré (French Mathematician, Theoretical Physicist & Mining Engineer)