Flow Rate Converter
Pump, HVAC and water-supply flows in every unit, with fill time and pipe velocity.
Type a flow in plain words — “100 lpm to gpm”, “1000 cfm in m3/h”, “10 MLD to L/s” — or use the boxes below.
Rounded · gpm (US) = L/min ÷ 3.785411784 · 1 L/min ≈ 0.2641720524 gpm (US)
- Litre per minute (LPM): 1 L/min = 0.06 m³/h (taps, showers and pumps; also written LPM)
- US gallon per minute (gpm): one US gallon (231 in³ = 3.785411784 L) a minute ≈ 0.227 m³/h (pumps, wells, plumbing)
Flow calculators
They use the flow above, in whatever unit you typed it.
Type the tank volume to see how long it takes to fill at this flow.
Use the inside diameter: a pipe’s nominal size is not its bore.
Type the pipe’s inside diameter to see the mean water velocity.
Per-person demand (LPCD) depends on the place and the design standard; use the figure your utility or design manual gives.
Type the number of people.
100 L/min in every unit
Select a unit to convert to it. Values marked ≈ are rounded; all others are exact.
| Unit | Value | Copy |
|---|---|---|
| Metric | ||
| ≈ 0.001666666667 | ||
| 6 | ||
| 144 | ||
| ≈ 1.666666667 | ||
| from | 100 | |
| 6,000 | ||
| 1,44,000 | ||
| 1,00,000 | ||
| 0.144 | ||
| US customary | ||
| to | ≈ 26.41720524 | |
| ≈ 1,585.032314 | ||
| ≈ 38,040.77554 | ||
| ≈ 0.03804077554 | ||
| ≈ 3.531466672 | ||
| ≈ 0.05885777787 | ||
| ≈ 211.8880003 | ||
| ≈ 905.7327509 | ||
| Imperial (UK) | ||
| ≈ 21.99692483 | ||
| ≈ 1,319.81549 | ||
Convert a list of values
Up to 1,000 lines. Fractions (3/4), mixed numbers (1 1/2) and grouped digits (1,250) are fine.
| Value | Result |
|---|
About the Flow Rate Converter
Convert volume flow rates for pumps, fans, HVAC and water supply: cubic metres per second, hour and day, litres per second, minute (LPM), hour (LPH) and day, millilitres per minute, million litres per day (MLD), US gallons per minute, hour and day, million US gallons per day (MGD), cubic feet per minute (CFM), second and hour, oil barrels per day and imperial gallons per minute and hour. Type in either box and the table underneath shows the flow in every unit.
The factors are exact: a US gallon is 231 cubic inches (3.785411784 L), an imperial gallon 4.54609 L and a cubic foot 28.316846592 L, so 1,000 CFM is exactly 1,699.01079552 m³/h. Under the converter, Flow calculators work out how long a tank takes to fill at the flow, the mean velocity in a pipe, and the litres per person per day for a population — or the flow that a population needs.
How to use it
- Type a number in From and pick its unit, then pick the unit you want in To — or type
100 lpm to gpm,1000 cfm in m3/hor10 MLD to L/sin Quick convert and press Enter. - Read the result and its formula, or every unit in the table underneath. Values marked ≈ are rounded.
- Under Flow calculators, pick Tank fill time and type a tank volume, Pipe velocity and type the pipe’s inside diameter, or Water per person and type the number of people (and, if you want the flow they need, the litres per person per day).
- Copy the result or a link, download the table as CSV, or open Convert a list of values for a column of readings.
Examples
100 L/min to US gpm
≈ 26.42 gpm (US)
100 ÷ 3.785411784.
1 m³/h to L/min
≈ 16.667 L/min
1,000 L ÷ 60 minutes.
1,000 CFM to m³/h
1,699.01079552 m³/h (exact)
1,000 × 60 × 0.028316846592 m³.
10 MLD to L/s
≈ 115.74 L/s
10,000,000 L ÷ 86,400 s.
1 MGD to MLD
3.785411784 MLD (exact)
50,000 bbl/d to m³/day
7,949.3647464 m³/day (exact)
A barrel is 42 US gallons.
1,000 L tank at 20 L/min
50 min
Time = volume ÷ flow.
100 L/min in a 25 mm bore
≈ 3.4 m/s
v = Q ÷ (π × d² ÷ 4).
20,000 people at 150 L a day
3 MLD = 3,000 m³/day ≈ 34.72 L/s
Common uses
- Pump and well ratings in L/min, m³/h or US gpm.
- Fan, duct and compressor airflow in CFM and m³/h.
- Water and sewage treatment capacities in MLD, m³/day and MGD.
- Showers, taps and irrigation in L/min, L/h and gph.
- River and canal flows in m³/s (cumecs) and ft³/s (cusecs).
- How long a tank, pool or drum takes to fill or drain at a given flow.
US and imperial gallons
A US gallon is 231 cubic inches, exactly 3.785411784 L (NIST Handbook 44, Appendix C); an imperial gallon is 4.54609 L (UK Weights and Measures Act 1985, Schedule 1). So 1 imperial gpm is about 1.201 US gpm, and a flow in gallons per minute is about 20 % different depending on which gallon it uses — a datasheet should say which. The oil barrel is 42 US gallons (158.987294928 L).
- US gpm = L/min ÷ 3.785411784
- imperial gpm = L/min ÷ 4.54609
- CFM = m³/h ÷ 1.69901079552
MLD, KLD and LPCD
MLD is a million litres per day, which is 1,000 m³/day or about 11.574 L/s. KLD (kilolitres per day) is the same as m³/day. Water supply in India is planned in LPCD, litres per capita (person) per day, and the flow a population needs is simply people × LPCD:
- MLD = people × LPCD ÷ 1,000,000
- L/s = people × LPCD ÷ 86,400
The per-person figure itself depends on the place, the kind of supply and the design standard; use the one your utility or design manual sets.
Mass flow and gas flow
Kilograms or tonnes per hour measure a mass flow. Turning one into a volume flow needs the density of the fluid: L/h = kg/h ÷ density in kg/L. Water is close to 1 kg per litre, but oils, fuels, milk and syrups are not — the Liters to KG Converter has typical densities.
Gas flows in SCFM or Nm³/h are referenced to standard or normal conditions of pressure and temperature, so they measure an amount of gas rather than the volume flowing at the actual pressure. They need the gas conditions to convert, and the reference conditions differ between standards, so they are not converted here.
The calculators
- Tank fill time = volume ÷ flow. 1,000 L at 20 L/min takes 50 minutes; the same time empties it at that flow.
- Pipe velocity = flow ÷ the bore area, v = Q ÷ (π × d² ÷ 4). 100 L/min in a 25 mm bore is about 3.4 m/s.
- Water per person: the flow × 86,400 s ÷ the number of people gives litres per person per day; people × litres per person per day gives the flow.
Limitations
- Only volume flow rates are converted. Mass flows need a density, and gas flows at standard or normal conditions need the gas pressure and temperature.
- Pipe velocity is the mean velocity in a full round pipe. For the pressure loss along it, use the Pipe Pressure Drop Calculator.
- Fill time assumes the flow stays the same. Many pumps, centrifugal pumps in particular, deliver less as the height they lift to rises, so a tank filled from below may fill more slowly towards the top.
- Gallons per minute differ by about 20 % between US and imperial gallons: check which one a datasheet uses.
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Frequently asked questions
How do I convert litres per minute to gallons per minute?
Divide by 3.785411784 for US gallons or by 4.54609 for imperial gallons. 100 L/min is 26.42 US gpm or 22.00 imperial gpm.
How many litres per minute is 1 m³/h?
16.667 L/min: a cubic metre is 1,000 litres and an hour is 60 minutes. 1 L/s is 3.6 m³/h.
What is 1 CFM in m³/h?
1 cubic foot per minute is 1.699 m³/h (exactly 1.69901079552), and 1 m³/h is 0.5886 CFM.
What does MLD mean?
Million litres per day. 1 MLD = 1,000 m³/day ≈ 11.574 L/s ≈ 0.264 MGD. It is the usual unit for water and sewage treatment plant capacity in India.
How do I convert kg/h to L/h?
Divide by the density in kg/L. For water (about 1 kg/L) the numbers are nearly the same; 900 kg/h of an oil with a density of 0.9 kg/L is 1,000 L/h.
How long will my tank take to fill?
Divide its volume by the flow. A 1,000 L tank at 20 L/min takes 50 minutes; at 5 US gpm a 500-gallon tank takes 100 minutes. Use Tank fill time under the converter.
What are cumecs and cusecs?
A cumec is a cubic metre per second and a cusec a cubic foot per second, both used for rivers, canals and dams. 1 cumec ≈ 35.31 cusecs.