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Flow Rate Converter

Convert volumetric flow rate between GPM, L/min, L/s, CFM, m³/h, m³/s, GPH and mL/s instantly in your browser.

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About this tool

Convert a volumetric flow rate between eight common units, entirely in your browser with nothing uploaded. Choose a From unit and a To unit, type a value, and the result updates live; the ⇄ button swaps the two units.

Every unit is defined by an exact factor to the SI base unit, the cubic metre per second (m³/s): the value is multiplied by the From factor to get m³/s, then divided by the To factor. US liquid gallons use 1 gal = 3.78541 L, so 1 GPM = 3.78541 L/min ≈ 6.309 × 10⁻⁵ m³/s, and CFM uses 1 ft³ = 0.0283168 m³. For example 1 US gallon per minute converts to about 3.785 litres per minute.

Useful for plumbing, pumps, HVAC air handling (CFM), irrigation, aquariums and process engineering. Note these are US gallons, not imperial gallons, and that flow rate (volume per time) is different from the static volume converters — this tool always includes a per-time dimension.

Frequently asked questions

What base unit does the converter use?
The cubic metre per second (m³/s). Every unit has an exact factor to m³/s, so conversions route through it: value × from-factor ÷ to-factor.
How many litres per minute is 1 GPM?
One US gallon per minute is 3.78541 litres per minute, since a US liquid gallon is 3.78541 litres. So 1 GPM ≈ 3.785 L/min.
Are these US or imperial gallons?
US liquid gallons (3.78541 L). An imperial gallon is larger at about 4.546 L, so if your figures are UK/imperial the GPM and GPH values will differ.
What is CFM?
Cubic feet per minute, a common airflow unit for fans and HVAC. One cubic foot is 0.0283168 m³, so 1 CFM ≈ 4.719 × 10⁻⁴ m³/s ≈ 28.317 L/min.

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