What this converter does
This converter turns cubic feet per minute into litres per second and back. One CFM is about 0.472 L/s. Type a value, pick your units, and read the airflow instantly — handy when a fan is rated in CFM but your calcs are metric.
It also covers m³/h and m³/s. For air speed in a duct rather than volume flow, see the m/s to FPM converter.
The units it covers
Every unit here measures volumetric airflow, converting through cubic metres per second with a fixed ratio.
View all units & their values
| Unit | Symbol | Value | Mainly used |
|---|---|---|---|
| Cubic foot per minute | CFM | 0.000472 | US duct & fan sizing |
| Litre per second | L/s | 0.001 | Metric ventilation rates |
| Cubic metre per hour | m³/h | 0.000278 | European fan ratings |
| Cubic metre per second | m³/s | 1 | SI base — large ducts |
| Litre per minute | L/min | 0.0000167 | Small flows |
The formula
Each unit has a fixed value in m³/s, so converting between any two means going through it once:
result = value × factor_from ÷ factor_toWhere:
- value = the number you typed
- factor_from = the “from” unit’s value in m³/s
- factor_to = the “to” unit’s value in m³/s
Worked example
Convert a 400 CFM extract fan to litres per second.
1 CFM = 0.471947 L/s400 × 0.471947 = 188.8 L/sA 400 CFM fan moves about 189 L/s.
The units in this example
The US unit of volumetric airflow, used on fan and diffuser schedules and for duct sizing across North America.
- 1 CFM = 0.4719 L/s
- 1 CFM = 1.699 m³/h
- 100 CFM = 47.19 L/s
- 2119 CFM = 1 m³/s
The metric unit of airflow used in ventilation codes and rates-per-person calculations across most of the world.
- 1 L/s = 2.119 CFM
- 1 L/s = 3.6 m³/h
- 10 L/s = 21.19 CFM
- 1000 L/s = 1 m³/s
FAQ
Sources
ASHRAE — ventilation standards · US EPA — indoor air quality