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Flow Rate Unit Converter (L/min, m³/h, GPM, CFM)

Convert volumetric flow rate between L/s, L/min, L/h, m³/h, m³/s, US and UK gallons per minute (GPM), gallons per hour and CFM — for pumps, plumbing, irrigation and ventilation.

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How it works

value in target unit = value × (m³/s per source unit) ÷ (m³/s per target unit) · 1 GPM (US) = 3.785411784 L/min · 1 CFM = 28.3168466 L/min · 1 m³/h = 16.6667 L/min

Volumetric flow is volume per unit of time; every unit here is converted through cubic meters per second. Pumps and faucets are rated in liters per minute or US gallons per minute, water mains and industrial pumps in m³/h, and fans and air compressors in cubic feet per minute (CFM). The US gallon (3.785 L) and UK gallon (4.546 L) give different GPM figures, so choose the right one.

Worked example

100 L/min ÷ 3.785411784 L per US gallon = 26.417 GPM (US). The same flow is 6 m³/h or 3.531 CFM.

Sources: NIST SP 811, Appendix B — Conversion factors · NIST — Unit conversion (SI and US customary)

Frequently asked questions

How do I convert L/min to GPM?

Divide by 3.785 for US gallons: 50 L/min ÷ 3.785 = 13.2 GPM. For UK gallons divide by 4.546.

How do I convert m³/h to L/min?

Multiply by 1,000 and divide by 60, i.e. × 16.667: 3 m³/h = 50 L/min.

How many CFM is 1 m³/h?

1 m³/h = 0.5886 CFM, and 1 CFM = 1.699 m³/h. A 100 CFM bathroom fan moves about 170 m³/h.

What flow does a garden hose deliver?

A typical 5/8″ hose at household pressure gives roughly 20–40 L/min (5–10 GPM); check yours with the garden hose flow rate calculator.

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This calculator is for educational purposes. Double-check important results before acting on them.