Air Changes Per Hour Calculator
Air changes per hour for a room, the flow a target rate needs, and the time for one complete change.
Results
Air changes per hour
5.8333
1/h
Volume
60.000
m³
Flow rate
360.00
m³/h
Flow rate
97.222
L/s
Minutes
10.286
min
What this tool does
Commonly cited design rates are around 6 to 8 changes an hour for a bathroom, 10 to 15 for a kitchen, 4 to 6 for an office and much higher for workshops and laboratories — but the binding numbers come from the ventilation regulation where you are building. The time for one full change is the figure that matters after cooking or a shower: at six changes an hour it is ten minutes.
Formula
ACH = flow rate ÷ room volume
Variables
| Symbol | Meaning | Unit |
|---|---|---|
qq | Flow rate | m³/h |
ar | Area | m² |
hh | Height | m |
tg | Target air changes | — |
AC | Air changes per hour | 1/h |
VL | Volume | m³ |
QR | Flow rate | m³/h |
QS | Flow rate | L/s |
MN | Minutes | min |
Worked example
- Flow rate350 m³/h
- Area24 m²
- Height2.5 m
- Target air changes6
- Air changes per hour5.8333 1/h
- Volume60.000 m³
- Flow rate360.00 m³/h
- Flow rate97.222 L/s
- Minutes10.286 min
Limitations
- For work that must comply with a standard or be signed off, check the result against the applicable code and have it reviewed by a qualified engineer.
- The default values are typical reference figures, not measurements of your situation. Replace them with your own data whenever you have it.
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.