CFM vs cubic meters per hour
Quick answer
CFM and m³/h both measure volume flow. CFM uses cubic feet per minute; m³/h uses cubic meters per hour. Converting units changes the number, not the airflow stream, fan performance, or design requirement.
Comparison table
| Factor | CFM | m³/h |
|---|---|---|
| Volume basis | Cubic feet | Cubic meters |
| Time basis | Minute | Hour |
| Conversion | 1 CFM | 1.69901082 m³/h |
| Meaning after conversion | The same stated volume-flow rate. | |
Formula and examples
m³/h = CFM × 1.69901082
CFM = m³/h ÷ 1.69901082
CFM = m³/h ÷ 1.69901082
| CFM | m³/h |
|---|---|
| 50 | 85.0 |
| 100 | 169.9 |
| 240 | 407.8 |
| 500 | 849.5 |
Use the unit conversion safely
Keep the same air-stream label before and after conversion. For example, 240 CFM supply air becomes about 408 m³/h supply air; it does not become outdoor ventilation air. When a calculation uses velocity, area, pressure, or room volume, convert every associated input consistently.
FAQ
Are CFM and m³/h equivalent airflow rates?
Yes. They express the same volume-flow rate in different units after conversion.
Can I use a converted flow to choose a duct size?
Only as one input. Duct design also depends on shape, area, velocity, pressure loss, fittings, and the available fan pressure.