Flow Rate Converter
Convert between L/s, L/min, m³/h, gal/min and ft³/s.
Results update as you type.
How it works
A flow rate converter restates a volumetric flow — how much fluid passes a point per unit of time — in a different unit, moving between litres per second and per minute, cubic metres per hour, US gallons per minute and cubic feet per second. It reduces your figure to litres per second, used here as the common base, then scales out to the unit you choose, so one mechanism covers pumps, plumbing, irrigation, HVAC ducting and river or channel flows alike. This matters because flow rate is expressed in different units across trades and regions, and mixing them can badly mis-size a system. Plumbers and pump specifications in the United States use gallons per minute; European and scientific work uses litres per second or cubic metres per hour; ventilation and gas flows sometimes use cubic feet per second; drip irrigation is often litres per minute. Choosing a pump or pipe from a spec in the wrong unit can leave a system starved or wastefully oversized. The convert-through-litres-per-second method is used because every flow unit has a fixed ratio to that base — one litre per minute is one-sixtieth of a litre per second, one US gallon per minute is about 0.0631 L/s, one cubic metre per hour is about 0.278 L/s — so pivoting through it keeps results consistent and needs only one factor per unit. Plumbers, mechanical and process engineers, irrigation designers and HVAC installers all rely on a flow rate converter whenever a specification arrives in an unfamiliar unit.
Convert to litres per second via known factors, then to the target unit
The input is multiplied by its unit's fixed number of litres per second to express the flow in that base, then divided by the target unit's value to complete the conversion. Because a volumetric flow is a volume divided by a time, and both reduce to constants against the litre and the second, every flow unit has a fixed ratio to litres per second, so chaining through that single base is exact for every pairing with just one stored factor per unit.
Source:International System of Units (SI) — NIST
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter value, from and to.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Converted flow rate updates instantly as you type — no button to press.
Frequently asked questions
How do I convert GPM to litres per minute?
Multiply US gallons per minute by about 3.785 to get litres per minute, since one US gallon is about 3.785 litres. So 10 GPM is roughly 37.85 L/min. To reverse it, divide litres per minute by 3.785. Note that the imperial UK gallon is larger, about 4.546 litres, so a UK-sourced GPM figure would use that factor instead; this converter uses US gallons.
What is the difference between L/s and m³/h?
Litres per second and cubic metres per hour both measure volumetric flow but on very different time and size scales. One litre per second equals 3.6 cubic metres per hour, because there are 1,000 litres in a cubic metre and 3,600 seconds in an hour. So a pump rated 5 L/s moves 18 m³/h. Larger industrial and water-supply flows are often quoted in m³/h for convenience.
How do I convert cubic feet per second to litres per second?
Multiply cubic feet per second by about 28.32 to get litres per second, since one cubic foot is about 28.32 litres. So a stream at 2 ft³/s flows at about 56.6 L/s. Cubic feet per second, often written cfs, is common in US hydrology for rivers and channels, while litres per second suits smaller engineered systems and scientific measurement.
Does this use US or imperial gallons?
This converter uses US gallons, where one gallon is about 3.785 litres and one US gallon per minute is about 0.0631 litres per second. The UK imperial gallon is larger at about 4.546 litres, so an imperial GPM figure would convert to a proportionally higher metric flow. If your specification is British, adjust for the larger gallon before comparing, or the result will read low.
Why convert flow rate through litres per second?
Litres per second is a convenient, coherent base close to the SI cubic-metre-per-second unit, so every other flow unit has a fixed ratio to it. Using it as the pivot means the converter needs only one factor per unit rather than a separate rule for each pair, keeps results exact, and sits at a practical scale for the pump, plumbing and irrigation flows people most often need to compare.