Flow Rate Converter
Converts volumetric flow between plumbing, pumping and ventilation units. CFM is the standard for air handling; gpm and L/min for water.
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The formula
result = value × (from factor ÷ to factor)
Each flow rate unit is defined by its size relative to the cubic metre per second, so converting between any two is a single multiplication.
Every flow rate unit
| Unit | Symbol | In one cubic metre per second |
|---|---|---|
| cubic metre per second | m³/s | 1 |
| cubic metre per hour | m³/h | 3,600 |
| litre per second | L/s | 1,000 |
| litre per minute | L/min | 60,000 |
| US gallon per minute | gpm | 15,850.323 |
| cubic foot per minute | cfm | 2,118.88 |
Frequently Asked Questions
How many litres per minute is 1 US gpm?
3.7854 L/min — the same factor as gallons to litres, since the time unit is unchanged.
What is CFM?
Cubic feet per minute, the standard measure of air movement for fans, extractors and HVAC ducting. 1 CFM is 1.699 m³/h.
How do I work out flow from pipe size and velocity?
Flow = cross-sectional area × velocity. A 50 mm pipe (0.00196 m²) at 1 m/s carries 0.00196 m³/s, or about 118 L/min.