This volumetric flow rate converter changes a flow between cubic meters per second, liters per second and per minute, cubic meters per hour, US gallons per minute (gpm), cubic feet per second and per minute (CFM) and barrels per day. The factors are exact: 1 US gallon = 3.785411784 L, so 1 gpm = 3.785411784 L/min, and 1 ft³ = 28.316846592 L, so 1 CFM ≈ 1.69901 m³/h.
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How to use the volumetric flow rate converter
- Enter the flow, for example 10 from a pump curve in gpm.
- In the volumetric flow rate converter, choose its unit and the target unit.
- Read the volumetric flow rate converter result: 10 gpm = 37.85 L/min = 2.271 m³/h.
For gpm to m³/h, multiply by 0.227125. Water and air flows use the same units; only the typical ranges differ.
What is volumetric flow rate?
Volumetric flow rate is the volume of fluid passing a point per unit time. The SI unit is the cubic meter per second; plumbing and pumps often use liters per minute or US gallons per minute (GPM), and HVAC uses cubic feet per minute (CFM).
Conversion formula
The volumetric flow rate converter stores every unit as a multiple of the base unit, the cubic meter per second (m³/s). To convert:
value in target unit = value × (factor of source unit ÷ factor of target unit)
where each factor is the size of the unit in cubic meters per second.
Common volumetric flow rate conversions
| From | To | 1 unit equals |
|---|---|---|
| liter per minute (L/min) | US gallon per minute (gpm US) | 0.2641721 gpm US |
| US gallon per minute (gpm US) | liter per minute (L/min) | 3.785412 L/min |
| cubic foot per minute (ft³/min) | liter per second (L/s) | 0.4719474 L/s |
Volumetric flow rate converter worked example
Convert 25 liters per minute to US gallons per minute:
- Factor of L/min = 1.66667 × 10−5 m³/s
- Factor of gpm US = 6.30902 × 10−5 m³/s
- 25 × 1.66667 × 10−5 ÷ 6.30902 × 10−5 = 6.604301 gpm US
Volumetric flow rate unit reference
| Unit | Symbol | Group | Equals (m³/s) |
|---|---|---|---|
| Cubic Meter per Second | m³/s | SI | 1 |
| Liter per Second | L/s | Metric | 0.001 |
| Liter per Minute | L/min | Metric | 1.66667 × 10−5 |
| Cubic Meter per Hour | m³/h | Metric | 0.0002777777778 |
| US Gallon per Minute | gpm US | US | 6.30902 × 10−5 |
| US Gallon per Second | gal/s US | US | 0.003785411784 |
| Cubic Foot per Second | ft³/s | US/Imperial | 0.02831684659 |
| Cubic Foot per Minute | ft³/min | US/Imperial | 0.0004719474432 |
| US Barrel per Day | bbl/d | Oilfield | 1.84013 × 10−6 |
Reverse factors for each volumetric flow rate unit
The volumetric flow rate converter reference table gives each unit in cubic meter per seconds. To go the other way, divide by that factor; the list below does the division for you.
- Liter per Second (L/s), Metric: 1 L/s = 0.001 m³/s, so 1 m³/s = 1,000 L/s.
- Liter per Minute (L/min), Metric: 1 L/min = 1.66667 × 10−5 m³/s, so 1 m³/s = 59,999.88 L/min.
- Cubic Meter per Hour (m³/h), Metric: 1 m³/h = 0.0002777778 m³/s, so 1 m³/s = 3,600 m³/h.
- US Gallon per Minute (gpm US), US: 1 gpm US = 6.30902 × 10−5 m³/s, so 1 m³/s = 15,850.32 gpm US.
- US Gallon per Second (gal/s US), US: 1 gal/s US = 0.003785412 m³/s, so 1 m³/s = 264.1721 gal/s US.
- Cubic Foot per Second (ft³/s), US/Imperial: 1 ft³/s = 0.02831685 m³/s, so 1 m³/s = 35.31467 ft³/s.
- Cubic Foot per Minute (ft³/min), US/Imperial: 1 ft³/min = 0.0004719474 m³/s, so 1 m³/s = 2,118.88 ft³/min.
- US Barrel per Day (bbl/d), Oilfield: 1 bbl/d = 1.84013 × 10−6 m³/s, so 1 m³/s = 543,439.9 bbl/d.
Plumbing fixture flow rates
US federal law caps showerheads at 2.5 gpm, and the EPA WaterSense label requires 2.0 gpm or less. In metric units:
| Fixture | Flow (gpm) | L/min | m³/h |
|---|---|---|---|
| Showerhead, US federal maximum | 2.5 | 9.46 | 0.568 |
| Showerhead, EPA WaterSense label | 2 | 7.57 | 0.454 |
| Bathroom faucet, WaterSense | 1.5 | 5.68 | 0.341 |
| Kitchen faucet, US federal maximum | 2.2 | 8.33 | 0.5 |
For gpm to L/min, multiply by 3.78541.
Air flow: CFM to m³/h
Fans and HVAC equipment are rated in cubic feet per minute in the US and in m³/h or L/s elsewhere. For CFM to m³/h, multiply by 1.69901:
| CFM | m³/h | L/s |
|---|---|---|
| 50 | 85 | 23.6 |
| 80 | 135.9 | 37.8 |
| 100 | 169.9 | 47.2 |
| 150 | 254.9 | 70.8 |
| 200 | 339.8 | 94.4 |
| 400 | 679.6 | 188.8 |
| 1000 | 1,699 | 471.9 |
Pair with the mass flow rate converter when density matters.
Filling and draining times
Flow rate turns straight into time. A garden hose delivering 10 L/min fills a 1,000 L pond in 100 minutes. The same hose is about 2.6 US gpm. If a pump label says 1,200 gal/h, the volumetric flow rate converter gives 20 gpm, or about 75.7 L/min, so a 3,000 L tank empties in about 40 minutes.
Related converters and calculators
Related flow tools:
- Mass flow rate converter: kg/h and lb/h
- Molar flow rate converter: mol/s and kmol/h
- Volume converter: L, gal, m³
- Pressure converter: psi, bar, kPa
- Density converter: kg/m³ and g/cm³
Sources
NIST Special Publication 811, Appendix B; EPA WaterSense: Showerheads.
Questions about this calculator
What is the SI unit of volumetric flow rate?
Cubic meter per second (m³/s).
How do I convert gpm to L/min?
Multiply by 3.78541. For example, 5 gpm = 18.93 L/min.
How do I convert gpm to m³/h?
Multiply by 0.227125. For example, 100 gpm = 22.71 m³/h.
How do I convert m³/h to gpm?
Multiply by 4.40287. For example, 10 m³/h = 44.03 gpm.
How do I convert CFM to m³/h?
Multiply by 1.69901. For example, 200 CFM = 339.8 m³/h.
What flow does a WaterSense showerhead have?
2.0 gallons per minute or less, about 7.6 L/min, compared with the 2.5 gpm US federal maximum.
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
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