Supported units
- Cubic meter per second (m³/s)
- Cubic meter per hour (m³/h)
- Liter per second (L/s)
- Liter per minute (L/min)
- US gallon per minute (gpm)
Conversion tool
Volumetric Flow Rate Converter
Select a category, enter a value, and convert between compatible units.
Flow rate units explained
Volumetric flow rate measures the volume of fluid passing a point during a given period. It is commonly expressed in cubic metres, litres or gallons per unit of time.
Common engineering uses
Flow rate conversion is used for pumps, piping systems, water supply, ventilation and industrial processes.
Formula
Q = V / t = A × v
Volumetric flow rate is the volume of fluid passing a point per unit of time. For steady flow through a uniform cross-section, it also equals area multiplied by average fluid velocity.
- Q = volumetric flow rate, measured in m³/s
- V = fluid volume, measured in cubic metres (m³)
- t = elapsed time, measured in seconds (s)
- A = flow cross-sectional area, measured in m²
- v = average fluid velocity, measured in m/s
Common conversions
| From | Equivalent value |
|---|---|
| 1 cubic metre per second (m³/s) | 3,600 cubic metres per hour (m³/h) |
| 1 cubic metre per hour (m³/h) | 16.6667 litres per minute (L/min) |
| 1 litre per second (L/s) | 60 L/min = 3.6 m³/h |
| 1 litre per minute (L/min) | 0.06 cubic metre per hour (m³/h) |
| 1 US gallon per minute (US gpm) | approximately 3.78541 L/min |
| 1 Imperial gallon per minute (Imp gpm) | approximately 4.54609 L/min |
Convert 120 L/min to m³/h
- Use the relationship 1 L/min = 0.06 m³/h.
- Multiply 120 by 0.06.
- 120 × 0.06 = 7.2 m³/h.
120 L/min = 7.2 m³/h
For gases, always check whether the stated flow refers to actual or standard reference conditions before comparing values.
Engineering applications
- Sizing pumps and checking operating points in piping systems.
- Designing water-supply, drainage and irrigation systems.
- Specifying ventilation and air-distribution equipment.
- Monitoring dosing, cooling and industrial process flows.
- Comparing flowmeters and equipment specified using different volume and time units.
Common mistakes
- Confusing US gallons with Imperial gallons. The two gallon definitions produce different gpm values.
- Mixing seconds, minutes and hours when converting the time component of a flow unit.
- Confusing volumetric flow rate with mass flow rate. Converting between them requires fluid density.
- Comparing gas-flow values measured at different pressure and temperature reference conditions.
- Assuming a pump's rated flow will remain constant as system pressure or head changes.
Frequently asked questions
How many L/min are in one m³/h?
One cubic metre per hour is approximately 16.6667 litres per minute.
How many m³/h are in one L/s?
One litre per second equals exactly 3.6 cubic metres per hour.
Are US gpm and Imperial gpm the same?
No. One US gallon is approximately 3.78541 litres, while one Imperial gallon is approximately 4.54609 litres.
What is the difference between volumetric and mass flow rate?
Volumetric flow measures volume per time. Mass flow measures mass per time. They are related through the fluid density.
Does a flow conversion account for pressure?
No. A direct unit conversion changes only the unit. Pressure and temperature corrections must be applied separately when required, especially for gases.