CFM to CMH Calculator
Convert between CFM (Cubic Feet per Minute) and CMH (Cubic Meters per Hour) for air purifiers and HVAC systems. Essential for European and metric specifications.
Common in US HVAC and air purifier specifications
Metric unit for air flow rate
Quick Reference Table
| CFM | CMH (m³/h) | Typical Application | Room Size |
|---|---|---|---|
| 100 | 170 | Small bedroom purifier | ~11 m² / 120 ft² |
| 200 | 340 | Medium room purifier | ~22 m² / 240 ft² |
| 300 | 510 | Large room purifier | ~33 m² / 360 ft² |
| 400 | 680 | Living room/office | ~45 m² / 480 ft² |
| 500 | 850 | Commercial space | ~56 m² / 600 ft² |
Understanding CFM vs CMH in Different Regions
North America (CFM)
- •CADR ratings typically shown in CFM
- •ASHRAE standards use CFM
- •Room sizes in square feet
- •Popular brands: Honeywell, Levoit, Coway
Europe & Asia (CMH/m³/h)
- •Air flow in m³/h standard
- •EN standards use CMH
- •Room sizes in square meters
- •Popular brands: Philips, Dyson, Xiaomi
Conversion Formula
CFM to CMH
CMH = CFM × 1.69901Multiply CFM by 1.69901 to get cubic meters per hour
CMH to CFM
CFM = CMH × 0.58858Multiply CMH by 0.58858 to get cubic feet per minute
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Frequently Asked Questions
Why do European air purifiers use CMH instead of CFM?
Europe uses the metric system, where cubic meters per hour (m³/h or CMH) is the standard unit for measuring air flow. This aligns with room sizes measured in square meters and follows EN (European Norm) standards for HVAC and air purification systems.
How do I compare US and European air purifier specifications?
Use this calculator to convert between units. A good rule of thumb: 100 CFM ≈ 170 CMH. When shopping internationally, always check which unit is being used and convert to your familiar measurement system for accurate comparison.
What CMH do I need for my room?
For effective air purification, multiply your room volume (m³) by 5 to get the minimum CMH needed. For example, a 30m² room with 2.5m ceiling height (75m³) needs at least 375 CMH for 5 air changes per hour.
Do all countries in Europe use CMH?
Yes, all European Union countries and most other European nations use m³/h (CMH) as the standard. The UK traditionally used CFM but has largely transitioned to metric units. Always verify the units when purchasing air purifiers from different regions.