SettingsSettings for this calculationUS
The airflow in cubic feet per minute for the unit or branch you are checking.
Use the airflow the equipment was actually selected at, not the nominal tonnage. On two-stage and variable-capacity gear, convert the stage you are assessing — low stage and high stage on the same machine can be several hundred CFM apart, and an air change figure taken off the wrong one flatters the design.
Airflow
2,039 m³/h
Converted using an exact defined factor of 1.69901079552 m³/h per CFM. Exact by definition — the m³/h figure inherits whatever the CFM figure was worth, including which fan speed or stage it was read at.
- Conversion factor applied
- 1.7 m³/h per CFM
They open the calculator with your figures already in it
CFM to Cubic Metres per Hour Calculator: 2,039 m³/h — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- 1 ft = 0.3048 m exactly, so 1 ft³ = 0.028316846592 m³ exactly. An hour holds 60 minutes, so 1 CFM = 0.028316846592 × 60 = 1.69901079552 m³/h. That is exact and terminating; the 1.699010796 printed in many handbooks is the same number rounded to ten significant figures.
Inputs used
- Airflow (CFM)
- 1200
Intermediate steps
- Conversion factor applied
- 1.7 m³/h per CFM
Confidence note: Converted using an exact defined factor of 1.69901079552 m³/h per CFM. Exact by definition — the m³/h figure inherits whatever the CFM figure was worth, including which fan speed or stage it was read at.
What this calculation does not cover
- Dividing the converted m³/h by room volume gives TOTAL air changes, which is not a ventilation rate. Most systems recirculate, and only the outdoor-air fraction dilutes anything — a unit reading 4.5 ACH on 10% fresh air is delivering 0.45 outdoor air changes an hour to the people in the room. Where a specification, an infection-control standard or a residential ventilation rule sets an ACH figure, establish which of the two it means before quoting the number this page produces against it.
- That same division assumes the room mixes perfectly, and rooms do not. Supply and extract terminals set close together in one ceiling zone short-circuit, so a share of the converted airflow returns to the unit without ever reaching the occupied zone, and dead corners sit well below the nominal figure whatever the total says. Tall spaces compound it, because the volume in the denominator includes a great deal of air nobody is breathing.
Add the equipment this sizes
This result is a specification — 2,039 m³/h — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-06 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- 1 ft = 0.3048 m exactly, so 1 ft³ = 0.028316846592 m³ exactly. An hour holds 60 minutes, so 1 CFM = 0.028316846592 × 60 = 1.69901079552 m³/h. That is exact and terminating; the 1.699010796 printed in many handbooks is the same number rounded to ten significant figures.
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Your workspace
Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.
European, Middle Eastern and Asian fan, air handling and heat recovery data arrives in m³/h, so a job scheduled in CFM has to cross over before a unit can be selected or two submittals compared side by side. This page is for the mechanical contractor or plan reviewer doing that comparison. The gain specific to this direction is air changes: once the airflow reads in m³/h it divides straight into a room volume in cubic metres, and ACH falls out with no further arithmetic, where the CFM route needs a ×60 and a room measured in cubic feet. The trap is the neighbouring unit — a sheet quoting m³/min read as m³/h is out by sixty.