Flow Rate Converter – L/min, GPM, m³/h & CFM

Convert L/min, GPM, m³/h and CFM

Volumetric flow rate describes the volume of fluid or air that passes a point during a stated amount of time. This converter changes liters per minute, liters per second, cubic meters per hour or second, US and Imperial gallons per minute, US gallons per hour, and cubic feet per minute or second. Enter a value on either side and choose the labelled units; the other field updates immediately, so pump, pipe, fan and process specifications can be compared without dropping the time basis.

Liters per minute to US gallons per minute

One US liquid gallon is exactly 3.785411784 liters. Because both rates use minutes, converting L/min to US GPM only changes the volume unit: divide liters per minute by 3.785411784. Therefore 1 L/min is approximately 0.264172052358 US gal/min, and 10 L/min is approximately 2.64172 US gal/min. To reverse the conversion, multiply US GPM by 3.785411784. Open the dedicated L/min to GPM converter for its formula, table and worked example.

US GPM and Imperial GPM are not interchangeable

A US gallon is exactly 3.785411784 liters, while an Imperial gallon is exactly 4.54609 liters. A flow of 10 US GPM is therefore about 8.32674 Imperial GPM, even though both labels may be shortened to “gpm” in source material. This site writes US or Imperial explicitly in unit selectors and results. Confirm the gallon definition used by a pump curve, plumbing specification or equipment manual before applying a converted value.

Cubic meters per hour to cubic feet per minute

Ventilation and fan specifications often use m³/h in metric documents and CFM, meaning cubic feet per minute, in customary-unit documents. One cubic foot is exactly 0.028316846592 cubic meters. Accounting for the 60 minutes in an hour, 1 m³/h is approximately 0.588577778691 CFM, while 1 CFM is exactly 1.69901079552 m³/h under these definitions. For example, 100 m³/h is approximately 58.8578 CFM. Use m³/h to CFM or the reverse CFM to m³/h for focused conversion tables.

Keep the volume and time parts together

A flow-rate conversion changes both parts of a compound unit when necessary. One cubic meter contains exactly 1,000 liters, one hour contains exactly 3,600 seconds, and one minute contains exactly 60 seconds. That makes 1 L/s equal exactly 60 L/min and exactly 3.6 m³/h. Likewise, 1 ft³/s equals exactly 60 ft³/min. Treating m³/h as though it were only cubic meters, or CFM as though it were only cubic feet, produces a result off by the time conversion.

Volumetric flow is not mass flow

This calculator converts volume per time. Mass flow, such as kilograms per second, also depends on density. Ten liters per minute of water and ten liters per minute of air have the same volumetric flow but very different mass flow. Density can also change with temperature, pressure and composition. Do not convert a volumetric rate into a mass rate without a suitable density value and operating conditions.

Actual airflow and standard airflow

CFM may refer to actual cubic feet per minute at measured conditions or to a standardized flow adjusted to stated temperature and pressure. Those figures are not automatically equivalent. This unit converter treats CFM as a geometric volume rate and does not correct for altitude, temperature, humidity, pressure or gas composition. When a specification uses SCFM, ACFM or another qualified rate, follow its stated reference conditions before comparing values.

Using flow conversions for pumps, plumbing and ventilation

A converted rate does not determine pipe diameter, pump head, fan pressure, velocity, friction loss, cavitation margin or equipment efficiency. Those calculations require more information about the system. Use the volume converter for an amount without a time component and the pressure converter when a specification already provides pressure. For safety-critical water, gas, ventilation, chemical or medical systems, use the manufacturer’s data and a qualified design method.

Definitions, rounding and privacy

Linear calculations use liters per second as a shared base. The US liquid gallon, Imperial gallon, international foot and metric prefixes use their defined values, and results retain the stored factors before display rounding. The answer is only as reliable as the source measurement and unit label. Values are calculated locally in the browser and are not submitted with the conversion.