Air Purifier CADR Calculator
Calculate the CADR output your room needs to make sure your air purifier is actually powerful enough.
The CADR value (Clean Air Delivery Rate) shows how much clean air a purifier delivers per hour. Based on room size and target air changes per hour, calculate the CADR you need.
Pro tips
- Check for separate CADR values for dust, pollen and smoke when comparing devices.
- Keep doors and windows closed to maintain cleaning performance.
Frequently Asked Questions
What does CADR mean for air purifiers?
CADR (Clean Air Delivery Rate) shows how much purified air an air purifier delivers per hour, usually in m³/h. The higher the CADR value, the faster a room gets cleared of pollutants.
What CADR value do I need for my room?
As a rule of thumb, the CADR value should be about 4 to 5 times the room's floor area so the air gets fully exchanged roughly every 12 minutes. The calculator above works out the right value for your room size.
How often should the air in a room be exchanged?
For a noticeable improvement in air quality, manufacturers usually recommend an air exchange every 10-15 minutes (ACH 4-5). For allergies or smoke, more frequent exchange can be worthwhile.
Where should an air purifier be placed in a room?
Ideally free-standing in the room, with some distance from walls and furniture so air can be drawn in from all sides. Placing it near the main source (e.g. a window for pollen) usually works best.