Follow an airflow through a cubic-volume conversion and a 60-minute time change, then check the answer in reverse.
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The calculation explained
CFM = m³/h × (35.3146667 ÷ 60) ≈ m³/h × 0.588578
Both sides describe volume per time. First convert cubic meters to cubic feet, then change the hourly volume to a one-minute volume. Because volume has three dimensions, a length conversion factor must be cubed. The factor is approximately 35.3147 cubic feet in one cubic meter.
For 600 m³/h, the intermediate result is approximately 21,188.8 ft³/h. Dividing by 60 gives 353.1467… ft³/min, or about 353.15 CFM. Dividing the unrounded CFM result by the same combined factor returns 600 m³/h. Keep enough precision during the intermediate steps and round the final answer.
This operation changes units. It does not correct an air volume measured at one temperature and pressure to a different set of conditions. Before comparing equipment figures, check whether both flow rates use the same actual or standard conditions. A separate correction may be required when their measurement bases differ.
In this video
- 0:00 One airflow. Two unit systems.
- 0:13 Convert a volume, not a length
- 0:32 Change the time interval
- 0:46 Combine the two changes
- 1:04 600 m³/h → cubic feet per hour
- 1:20 Divide by 60 → 353.15 CFM
- 1:36 Check by converting back
- 1:54 Keep the air conditions consistent
- 2:14 Volume × 35.3147, time ÷ 60
Read the full video transcript
A fan moves six hundred cubic meters of air per hour. What is that in cubic feet per minute, or C F M? The airflow stays the same. We are changing the size of the volume unit and the length of the time interval.
First, look at one cubic meter. It is a cube one meter along each edge. Each edge is about three point two eight one feet, so the volume factor must be cubed. One cubic meter contains about thirty-five point three one five cubic feet. Using the length factor alone would be wrong.
Next, change per hour to per minute. At a steady rate, the volume moved in one hour is shared across sixty minutes. Each minute gets one sixtieth of the hourly volume. That is why we divide by sixty, rather than multiply.
Combine the steps. Multiply cubic meters per hour by thirty-five point three one five, then divide by sixty. Using more precise values gives a factor of approximately zero point five eight eight five seven eight. Cubic meters and hours cancel, leaving cubic feet per minute.
Now work the example in two stages. Six hundred cubic meters per hour becomes about twenty-one thousand one hundred eighty-nine cubic feet per hour. We have converted the volume, but the time unit is still hours. Keep that label visible so you do not stop too early.
Divide that hourly result by sixty. The answer is about three hundred fifty-three point one five cubic feet per minute. The shortcut gives the same result: six hundred times zero point five eight eight five seven eight. Round at the end, after the conversion.
To go back, divide C F M by the same factor. Using the unrounded answer returns six hundred cubic meters per hour. As a useful sense check, the numerical C F M value is smaller than the cubic meters per hour value, because the combined factor is less than one.
One important limit: this conversion changes units only. Air volume depends on temperature and pressure. A flow quoted at standard conditions and one quoted at actual conditions may need an additional correction before comparison. The unit factor alone cannot make those conditions match.
Remember the sequence: convert cubic meters to cubic feet, divide the hourly amount by sixty, and keep the measurement conditions consistent. For this example, six hundred cubic meters per hour is approximately three hundred fifty-three point one five C F M.
Sources and further reading
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