How flow unit conversion works
Volumetric flow is volume per time, so every unit is defined by a fixed factor relative to any other — this tool routes everything through m³/h:
The traps are not mathematical but definitional: which gallon (US 3.785 L vs imperial 4.546 L — a 20% difference), which barrel (the oil barrel of 42 US gallons is assumed here; other industries use other barrels), and actual vs standard gas volumes, which are different physical quantities, not different units.
Handy factors from 1 m³/h
| 1 m³/h equals | Value |
|---|---|
| L/s | 0.2778 |
| L/min | 16.667 |
| US GPM | 4.403 |
| Imperial GPM | 3.666 |
| BBL/day | 150.96 |
| CFM | 0.5886 |
Worked example
A pump datasheet states 250 US GPM; your hydraulic calculation needs m³/h:
- 250 × 0.22712 = 56.78 m³/h
- Cross-check in L/s: 56.78 ÷ 3.6 = 15.77 L/s
Field notes
- US vs imperial gallons is the classic 20% error. Old British-built plants and marine specs use imperial; anything American uses US. When a document just says "GPM", check its origin.
- BBL/day is an oilfield convention — 42 US gallons. Brewing and chemicals use different barrels; never assume.
- Nm³/h and SCFM are not in this grid deliberately — they are quantities at reference conditions. Converting them to actual flow requires pressure and temperature via the gas law.
Frequently asked questions
How many GPM is 1 m³/h?
1 m³/h equals 4.403 US gallons per minute (or 3.666 UK/imperial GPM — always confirm which gallon a datasheet means).
How many m³/h is 1000 barrels per day?
1000 oil barrels per day (42 US gallons each) is 6.624 m³/h, or about 159 m³/day.
Is this converter valid for gases?
For actual (operating) volumetric flow, yes — the units convert identically. But standard-condition gas units (Nm³/h, SCFM) also embed a pressure/temperature reference, so converting between actual and standard flow needs the gas law, not just a unit factor.
How do I convert kg/h to m³/h?
Divide the mass flow by the fluid density: m³/h = (kg/h) ÷ (kg/m³). Use our mass-volumetric flow converter, which does this with any density.
Provided for reference and education. Verify independently before use in safety-critical work. See our disclaimer.