Flow Rate Converter
m³/h, L/s, L/min and GPM — every unit at once.
Inputs
Result
Formula
| Base | 1 m³/h = 1000 L/h = 0.2778 L/s |
| Per second | 1 L/s = 60 L/min = 3.6 m³/h |
| US units | 1 GPM = 3.785 L/min = 0.2271 m³/h |
| Air | 1 CFM = 1.699 m³/h |
| Pipe sizing | Q = A × v with A = πd²/4 |
10 m³/h is 2.778 L/s, 166.67 L/min, 44.03 GPM or 5.886 CFM. A DN50 pipe at 1.5 m/s carries about 10.6 m³/h — the same order.
Flow rate unit reference
| Unit | Symbol | In m³/h | In L/s | Typical use |
|---|---|---|---|---|
| Cubic metre per hour | m³/h | 1 | 0.2778 | Pumps, cooling towers |
| Cubic metre per second | m³/s | 3600 | 1000 | Rivers, large flows |
| Litre per second | L/s | 3.6 | 1 | Supply design |
| Litre per minute | L/min | 0.06 | 0.01667 | Terminal use |
| US gallon per minute | GPM | 0.2271 | 0.0631 | Imported equipment |
| Cubic foot per minute | CFM | 1.699 | 0.4719 | Ventilation, fans |
FAQ
Why do pumps come in m³/h when pipes are sized in L/s?
Different habits: pump makers rate hourly output while hydraulic tables are per second, a factor of 3.6. Convert everything to L/s before reading tables, or 10 m³/h gets mistaken for 10 L/s and the pipe comes out 2.7 times too big.
What is an economic water velocity?
Usually 1.0-1.5 m/s, 0.6-1.0 below DN50 and 1.2-2.0 above DN100. Too slow and sediment settles with long stagnation; too fast and head loss grows with the square of velocity, bringing noise and erosion. Fire mains may run to 2.5 m/s.
How do I convert GPM to m³/h quickly?
Multiply by 0.227, or roughly 0.23; the other way, 1 m³/h ≈ 4.4 GPM. Imported pumps and cooling towers rate flow in GPM while domestic fittings are chosen in m³/h, and a conversion slip shows up as insufficient cooling water and high-temperature alarms.
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Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.