Unit Conversion
Flow Converter
Convert GPM, L/min, L/s, m³/h and CFM accurately. Calculate delivered volume, tank fill time and average pipe velocity with clear formulas.
Converted flow rate
—All equivalent values
Formula and calculation
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GPM uses the US liquid gallon, not the imperial gallon.
Try a useful example
Flow, tank and pipe planner
Volume delivered over time
Estimates assume a constant positive volume flow rate, a full circular pipe and no losses. Air volume depends on pressure and temperature; CFM is not a mass-flow or standardized-airflow value.
Flow rate, time and added volume
How these calculations work
Volume = flow rate × time. Fill time = target volume ÷ flow rate. Average pipe velocity = flow rate ÷ circular cross-sectional area. Enter the pipe’s inner diameter, not its outside diameter.
1 US GPM = 3.785411784 L/min · 1 CFM = 28.316846592 L/min
GPM to LPM and L/min to GPM
Gallons per minute and liters per minute are common in plumbing, pumps, irrigation, aquariums, and water system specifications.
- 1 GPM = 3.78541 L/min.
- 1 L/min = 0.264172 GPM.
- 10 GPM = 37.8541 L/min.
CFM and cubic flow units
Airflow and ventilation often use CFM, while engineering calculations may use cubic meters per second.
- 1 CFM = 0.000471947 m3/s.
- 1 m3/s = 2,118.88 CFM.
- Use volume flow units only when comparing the same type of flow.
Where flow rate matters
Use flow conversion for pump sizing, HVAC airflow, water filtration, irrigation, pool circulation, and lab or engineering examples.
- Liquids often use GPM or L/min.
- Air systems often use CFM.
- Large industrial systems often use m3/s or m3/h.
Related calculators
Flow often connects to volume, pressure, speed, and pipe or pump calculations.
Flow Converter FAQ
How do I convert GPM to LPM?
Multiply gallons per minute by 3.78541 to get liters per minute.
How do I convert L/min to GPM?
Multiply liters per minute by 0.264172 to get gallons per minute.
What does CFM mean?
CFM means cubic feet per minute, a common airflow unit.
Is flow rate the same as volume?
No. Volume is an amount, while flow rate is volume per unit of time.
Which flow unit should I use?
Use the unit expected by your pump, pipe, HVAC, or engineering reference, then convert if needed.
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