How this conversion works
Volumetric flow rate is volume per unit time. Each unit is converted to cubic meters per second by combining an exact volume definition with the time unit.
The US gallon is exactly 3.785411784 L and the Imperial gallon exactly 4.54609 L, so “GPM” values differ by about 20% between the two.
Formula: result = value × (base units per source unit) ÷ (base units per target unit)
Where this conversion is used
- Shower heads, faucets and pumps rated in L/min or GPM.
- Fan and HVAC airflow in cfm or m³/h.
- River and stream flows in cubic feet or cubic meters per second.
- Irrigation and dosing systems in L/h or gal/h.
Worked example: A 10 L/min shower head in US GPM
- One US gal/min = 3.785411784 L/min.
- 10 ÷ 3.785411784 = 2.6417 gal/min (US).
Unit definitions
| Unit | In cubic meters per second | Note |
|---|---|---|
| Cubic meter per second (m³/s) | 1 | |
| Cubic meter per hour (m³/h) | 0.0002777778 | |
| Liter per second (L/s) | 0.001 | |
| Liter per minute (L/min) | 0.0000166667 | |
| Liter per hour (L/h) | 2.77778e-7 | |
| Milliliter per minute (mL/min) | 1.66667e-8 | |
| US gallon per minute (gal/min (US)) | 0.0000630902 | |
| US gallon per hour (gal/h (US)) | 0.0000010515 | |
| Imperial gallon per minute (gal/min (Imp)) | 0.0000757682 | |
| Cubic foot per second (ft³/s) | 0.0283168466 | |
| Cubic foot per minute (ft³/min) | 0.0004719474 |
Liters per minute to US gallons per minute
| Liter per minute (L/min) | US gallon per minute (gal/min (US)) |
|---|---|
| 1 | 0.2642 |
| 5 | 1.3209 |
| 7.5 | 1.9813 |
| 10 | 2.6417 |
| 20 | 5.2834 |
| 50 | 13.2086 |
| 100 | 26.4172 |
US gallons per minute to liters per minute
| US gallon per minute (gal/min (US)) | Liter per minute (L/min) |
|---|---|
| 1 | 3.7854 |
| 1.5 | 5.6781 |
| 2 | 7.5708 |
| 2.5 | 9.4635 |
| 5 | 18.9271 |
| 10 | 37.8541 |
| 50 | 189.2706 |
Cubic feet per minute to cubic meters per hour
| Cubic foot per minute (ft³/min) | Cubic meter per hour (m³/h) |
|---|---|
| 50 | 84.9505 |
| 100 | 169.9011 |
| 200 | 339.8022 |
| 400 | 679.6043 |
| 1,000 | 1,699.0108 |
Things to watch for
- This converts volume flow only. Converting to mass flow (kg/s) requires the fluid's density.
Precision and sources
Results are calculated from the definitions above and rounded to 12 significant digits; the converter shows up to eight decimal places and the tables four. Reference: NIST Special Publication 811, Guide for the Use of the International System of Units, Appendix B.
Frequently asked questions
What does CFM mean?
Cubic feet per minute, common for fans and HVAC airflow. 100 cfm ≈ 169.9 m³/h.
Which gallon does GPM use?
In the US it means US gallons. In the UK older literature may mean Imperial gallons; choose the matching unit in the list.