When comparing air purifiers, you will inevitably come across the term CADR, often followed by a number and the unit m3/h. But what does that number actually mean, and why is it one of the most important specifications to look out for? We explain it below.
What does CADR mean?
CADR stands for Clean Air Delivery Rate, which is the amount of clean air an air purifier delivers per hour. The number indicates how many cubic meters of air the device can completely clear of contaminants per hour, expressed in m3/h. An air purifier with a CADR of 260 m3/h, such as the Dynter AirPure Plus PA244, can therefore theoretically clean 260 cubic meters of air per hour.
More than just fan flow rate
Important to know: CADR is not the same as the fan's air flow rate. It also takes the effectiveness of the filter into account. A device with a powerful fan but a weak filter might move a lot of air, but that air is not actually cleaned. CADR therefore combines two factors: how much air flows through the device, and how well the filter actually cleans that air.
CADR is measured by pollutant
Originally (via the American AHAM standard), CADR is measured separately for three types of contamination:
- Dust: larger particles such as house dust
- Smoke: very fine particles, similar in size to many types of particulate matter
- Pollen: larger particles that can cause allergy symptoms
In practice, a total CADR value is often stated, based on the most relevant or lowest of these categories. When comparing products, pay attention to whether a brand states the CADR for particulate matter/smoke, as that is often the most critical measure for indoor air quality.
Why is CADR more important than just wattage?
Many buyers look at the motor power (wattage) or the noise level, but that says little about the actual cleaning performance. A 45W device can, if well designed, have a higher CADR than a less efficient device with more power. What counts is the combination of air displacement and filtration quality, and that is exactly what CADR expresses.
How do you use CADR when choosing an air purifier?
A higher CADR means a device is suitable for a larger room, or that it refreshes the air in a smaller room more quickly. A rule of thumb (based on the AHAM guideline) is that the CADR should be approximately two-thirds of the floor area in square meters for effective cleaning within a reasonable time. For a detailed calculation including ceiling height and desired air exchange rate, read our article on calculating the right CADR for your room.
Example: the PA244
The AirPure Plus PA244 has a CADR of 260 m3/h and is suitable for up to approximately 55 m2. With a noise level between 28 and 60 dB, a HEPA13 filter (99.97% capture efficiency for particulate matter, pollen, bacteria, viruses, and microplastics) and three settings, this is an example of how CADR, room size, and filter quality come together in practice.
Our advice
Always compare air purifiers based on CADR in relation to the room in which you want to use the device, rather than just price or power. Our advice is to choose a model with a slightly higher CADR than strictly necessary in case of doubt, so that the device can run on a lower, quieter setting and still have sufficient capacity.