Airflow Conversion Chart
CFM to the three metric airflow units, tabulated from a 25 CFM bath fan to a 100,000 CFM air-handler bank: 1 CFM = 0.472 L/s = 1.699 m³/h. The second table runs the other direction, anchored on the round metric numbers that appear on European and global equipment submittals.
CFM → L/s / m³/h / m³/min
| CFM | L/s | m³/h | m³/min |
|---|---|---|---|
| 25 | 11.8 | 42.48 | 0.7079 |
| 50 | 23.6 | 84.95 | 1.416 |
| 100 | 47.19 | 169.9 | 2.832 |
| 150 | 70.79 | 254.9 | 4.248 |
| 200 | 94.39 | 339.8 | 5.663 |
| 300 | 141.6 | 509.7 | 8.495 |
| 400 | 188.8 | 679.6 | 11.33 |
| 500 | 236 | 849.5 | 14.16 |
| 750 | 354 | 1,274 | 21.24 |
| 1,000 | 471.9 | 1,699 | 28.32 |
| 1,500 | 707.9 | 2,549 | 42.48 |
| 2,000 | 943.9 | 3,398 | 56.63 |
| 3,000 | 1,416 | 5,097 | 84.95 |
| 4,000 | 1,888 | 6,796 | 113.3 |
| 5,000 | 2,360 | 8,495 | 141.6 |
| 7,500 | 3,540 | 12,743 | 212.4 |
| 10,000 | 4,719 | 16,990 | 283.2 |
| 15,000 | 7,079 | 25,485 | 424.8 |
| 20,000 | 9,439 | 33,980 | 566.3 |
| 30,000 | 14,158 | 50,970 | 849.5 |
| 50,000 | 23,597 | 84,951 | 1416 |
| 100,000 | 47,195 | 169,901 | 2832 |
Metric → CFM anchors
| Metric value | CFM |
|---|---|
| 50 L/s | 105.9 |
| 100 L/s | 211.9 |
| 250 L/s | 529.7 |
| 500 L/s | 1,059 |
| 1,000 L/s | 2,119 |
| 100 m³/h | 58.86 |
| 500 m³/h | 294.3 |
| 1,000 m³/h | 588.6 |
| 2,000 m³/h | 1,177 |
| 10,000 m³/h | 5,886 |
Which metric unit you'll meet where
L/s is the engineering unit — ASHRAE's SI editions, Canadian and Australian codes, and chilled-beam or lab-exhaust specs. m³/h dominates European product literature: ERVs, range hoods, fan coils, and rooftop units sized to EN standards. m³/min (sometimes written CMM) shows up on Japanese equipment. The conversions are exact volume identities, so the only judgment call is density — see the SCFM question below.
Size the airflow itself with the CFM calculator, tie it to tonnage in the BTU / tonnage / CFM chart, and check outdoor-air minimums against the ventilation rate chart.
Common questions
How do you convert CFM to L/s?
Multiply CFM by 0.472 — or divide by roughly 2.1 for a head estimate. A 1,000 CFM system is about 472 L/s. Going the other way, 1 L/s is 2.12 CFM.
How do you convert CFM to m³/h?
Multiply by 1.699 — or take CFM × 1.7 in your head. European ventilation specs and ERV/HRV documentation usually state m³/h: a 340 m³/h unit is a 200 CFM unit.
What is the difference between CFM and SCFM?
CFM is the actual volume rate at whatever density the air happens to be; SCFM restates it at the standard-air convention of 0.075 lb/ft³ (sea level, ~70 °F dry air). For comfort HVAC near sea level the two are effectively equal, but at altitude or high temperature the same mass of air occupies more volume — fan and coil selections at elevation must correct for it.