Volumetric flow rate is a fundamental parameter in process engineering, representing the volume of fluid passing through a cross-section per unit of time. The two units discussed here represent different systems of measurement: the US Customary system and the International System of Units (SI).
Gallons per Minute (GPM): Commonly used in the United States for residential plumbing, fire protection systems, and irrigation. It measures the number of US liquid gallons flowing through a pipe in one minute.
Cubic Meters per Second (m³/s): The SI derived unit for volumetric flow rate. It is the standard for large-scale industrial applications, municipal water treatment, and hydraulic engineering.
To convert between these units, we utilize the conversion factor \(1 \text{ GPM} \approx 6.30901964 \times 10^{-5} \text{ m}^3/\text{s}\). This factor is derived from the definition of a US gallon as exactly 231 cubic inches.
Gallon per minute (US) to Cubic meter per second Conversion Reference Table
Gallon per minute (US) (GPM)
Cubic meter per second (m³/s)
0.1
6.3090e-06
0.5
3.1545e-05
1.0
6.3090e-05
2.0
1.2618e-04
5.0
3.1545e-04
10.0
6.3090e-04
20.0
0.0013
50.0
0.0032
100.0
0.0063
500.0
0.0315
1000.0
0.0631
Conversion Example: 10 GPM to m³/s
To convert a flow rate of 10 GPM into SI units, multiply the value by the conversion factor:
Thus, a flow rate of 10 GPM is equivalent to approximately 0.0006309 m³/s.
The cubic meter per second is the SI coherent unit. Using SI units eliminates the need for conversion factors when calculating other physical properties like mass flow rate (kg/s) or fluid velocity, reducing the risk of calculation errors in complex engineering models.
Yes. The US gallon is defined as 3.78541 liters, while the Imperial (UK) gallon is defined as 4.54609 liters. This conversion factor specifically applies to the US liquid gallon.
"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)