Flow Rate Converter
Convert volumetric flow between litres per second, cubic metres per hour, GPM and CFM.
How to use this calculator
- 1Enter the value you want to convert.
- 2Pick the unit you are converting from and the one you want.
- 3The table below shows the same value in every other supported unit.
How the calculation works
result = (value × factor(from) ) / factor(to)- factor
- How many cubic metres per second one unit represents
Every value is converted to cubic metres per second first, then out to the target unit. This means n units need n factors rather than n² conversion pairs.
Volumetric flow is volume per unit time, so each factor is a volume factor divided by a time factor. Everything routes through cubic metres per second, the SI form.
CFM is standard for air (HVAC, compressors, fans) while GPM and L/min are standard for liquids, but they are the same quantity and convert directly.
Worked example
10 us gallon per minute to litre per minute
- 1.One us gallon per minute is 0.0000631 cubic metres per second, so 10 GPM is 0.0006309 cubic metres per second.
- 2.One litre per minute is 0.0000167 cubic metres per second, so divide: 0.0006309 ÷ 0.0000167 = 37.854118.
- 3.Put another way, 1 GPM = 3.7854118 L/min.
Result: 37.854118 L/min
What this assumes, and where it stops
Assumptions
- Conversion factors follow the internationally agreed definitions of each unit.
Limitations
- This converts volumetric flow only. Mass flow (kg/s, lb/hr) is a different quantity and requires the fluid density to convert between the two.
- Air flow in HVAC is sometimes quoted as "standard" CFM (SCFM), corrected to a reference temperature and pressure. Converting SCFM as if it were actual CFM ignores that correction.
Common questions
How do I convert GPM to litres per minute?
Multiply by 3.785, since a US gallon is exactly 3.785411784 litres. A 10 GPM pump moves 37.85 L/min. Note that a UK imperial gallon is larger (4.546 L), so British specifications using gallons will differ by about 20%.
Can I convert CFM to GPM?
Yes — they are both volumetric flow, so the conversion is direct (1 CFM ≈ 7.481 GPM). The units differ by convention rather than by physics: CFM is conventional for air and GPM for liquids, but nothing prevents converting between them.
Formula and content last reviewed on .
Results are estimates for information only, not professional advice.
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