Flow Rate Converter
Flow rate measures how much fluid moves past a point in a given time, and it is central to plumbing, irrigation, pumps, ventilation and process engineering. The difficulty is that flow is quoted in many different units depending on the trade and the country. A pump curve might use cubic metres per hour, a tap might be rated in litres per minute, a scientific calculation might use cubic metres per second, and an American specification might list gallons per minute, while an air system might be given in cubic feet per minute. This converter takes a volumetric flow rate in any of these units and instantly shows the equivalent in all of the others, with a full reference list so you can read off whatever figure your work requires. Enter a value, choose the unit you are converting from, choose the unit you want, and the answer appears immediately. The method is straightforward and transparent. Every unit is defined as a number of cubic metres per second, the SI unit of volumetric flow, which acts as the base. The calculator multiplies your value by the factor for the from unit to reach cubic metres per second, then divides by the factor for the to unit. A handy check is that one litre per second equals exactly 60 litres per minute. Be aware that US and UK gallons are not the same size, so the two gallons-per-minute figures differ, and that this tool handles volume flow rather than mass flow, which would also need the fluid density. It suits plumbers, irrigation designers, engineers and students who need a quick, reliable flow conversion.
Value in every unit
The formula
Each unit is defined by how many cubic metres per second it equals. To convert, the calculator multiplies your value by the factor for the unit you are converting from, which gives a value in cubic metres per second, then divides by the factor for the unit you want.
value in m³/s = value × factor[from]
result = value in m³/s / factor[to]
Conversion factors
| Unit | Cubic metres per second per unit |
|---|---|
| Cubic metres per second (m³/s) | 1 |
| Litres per second (L/s) | 0.001 |
| Litres per minute (L/min) | 0.0000166666667 |
| Cubic metres per hour (m³/h) | 0.000277777778 |
| US gallons per minute (US GPM) | 0.0000630901964 |
| UK gallons per minute (UK GPM) | 0.0000757682 |
| Cubic feet per minute (CFM) | 0.000471947443 |
Who this calculator is for
This converter is for plumbers, irrigation and HVAC designers, pump engineers and students who need to switch a flow rate between metric and imperial units when sizing pipes, pumps or ventilation.
What this calculator assumes
- The value you enter is numeric; anything non-numeric is treated as zero.
- Cubic metres per second is used as the base unit, and every other unit is defined relative to it.
- Gallons per minute use US and UK (imperial) gallons separately, which are different sizes.
- The tool converts volumetric flow, not mass flow, which would also require the fluid density.
- Results are rounded for display.
Frequently asked questions
How do I convert litres per second to litres per minute?
Multiply by 60. One litre per second is 60 litres per minute.
What is the difference between US and UK gallons per minute?
A US gallon is about 3.785 litres and a UK gallon is about 4.546 litres, so the two figures differ for the same flow.
What does CFM mean?
Cubic feet per minute, a flow rate common in ventilation. One CFM is about 28.3 litres per minute.
Is this a mass flow or volume flow converter?
It converts volumetric flow. Mass flow would also need the density of the fluid.
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