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Shopping for an air purifier can feel overwhelming, especially if you're unsure what to look for. One critical factor to consider is the CADR rating—an industry-standard measure of how effectively an air purifier cleans the air.
My guide breaks down what CADR means, why it matters, and how it can help you choose the perfect air purifier for your needs.
Key takeaways
What does CADR mean?
CADR stands for “clean air delivery rate." It measures how effective an air purifier is while running on a high fan speed.
Invented by the Association of Home Appliance Manufacturers (AHAM), CADR measures the volume of filtered air that an air purifier can deliver, in cubic feet per minute (CFM), for three different particle types:
The higher the CADR score for a particular particle type, the more effective the air purifier is at removing that type of particle.
According to the National Institute of Environmental Health Sciences, CADR only reflects the clean air at the highest fan speed and won’t reflect the purifier’s ability on a low fan speed.
Just keep in mind that CADR ratings are based on a standardized laboratory test and may not reflect real-world conditions or individual preferences.
Here is how CADR is calculated, with ACH meaning air changes per hour.
Related article: How to safely use air purifiers throughout your home
What is considered a good CADR rating for air purifiers?
I look for air purifiers rated above 310 CFM (cubic feet per minute) to ensure I’m getting a high-quality model.
A higher CFM rating means the purifier can move more air, which can be useful for larger rooms or spaces.
The Association of Home Appliance Manufacturers (AHAM) recommends a CADR of at least 100 for smoke, 100 for pollen, and 100 for dust for a 100-square-foot room.
As a rule of thumb, the CADR of your air cleaner should be equal to at least two-thirds of the room’s area. For example, a 10×12-foot room has an area of 120 sq. ft.
It would be best to have an air cleaner with a smoke CADR of at least 80. For wildfire smoke, AHAM recommends a Smoke CADR equal to the size of the room in square feet.
However, while important, the CADR rating is just one factor to consider when choosing an air purifier.
Here's a generalized table I created that also considers real-world factors such as the type of air purifier filter used, whether you're using a whole house air purifier versus a room air purifier, the air changes per hour, and the price of the air purifier.
Room Size | Recommended CADR minimum |
|---|---|
Under 100 square feet | 80 CFM |
Up to 200 square feet | 130 CFM |
200 - 400 square feet | 267 CFM |
400 - 600 square feet | 300 - 400 CFM |
600 - 800 square feet | 450 - 550 CFM |
800 - 1000 square feet | 500 - 600 CFM |
It's also important to mention that an air purifier with a lower CADR than its rated room size will still clean the air in that room. You will just need to run the air purifier longer.
ACLAB Notes
Always choose an air purifier that provides its CADR rating. The bigger the room, the higher is the CADR recommended.
Reasons to pay attention to CADR
- 1CADR shows the efficiency of air cleaning. A higher CADR ensures faster and more efficient air cleaning, especially in larger spaces.
- 2Room size. The CADR will help you determine if the air purifier will be powerful enough to clean your targeted room.
- 3CADR is broken down by pollutant (dust, pollen, or smoke), meaning you can ensure the number is suitable for your current issue.
- 4Products with a listed CADR can be trusted. This is a sign that a brand is well vetted and that they are following the regulatory and performance standards put in place by the AHAM.
Related article: Air purifier placement guide
How CADR for air purifiers is measured
The CADR (Clean Air Delivery Rate) rating is determined by an ANSI (American National Standards Institute) or AHAM AC-1 test that is completely standardized.
The test involves placing the air purifier unit in a chamber that measures 1008 cubic feet, which represents a 12×12 room with a 7-foot-high ceiling.
Once they have it running at full speed for 20 minutes, they expose it to specific types of pollutants, such as smoke, pollen, and dust.
The amount of pollutants removed from the air in the chamber is then measured over a specific period of time.
The results are used to calculate the CADR rating for each type of pollutant.
This test is accurate for the testing room, but studies have found that the CADR is typically slightly lower than the manufacturer's listing when used in real world application.
This is applicable to residential air cleaners, which involve the following limitations:
ACLAB Notes
CADR takes into account the clean air delivered after getting processed through all the different filtration stages including pre-filter, HEPA filter and activated carbon in most cases.
CADR ratings for popular air purifier brands
Air purifier manufacturers do all they can to set themselves apart from the competition. Part of that is ensuring their purifiers have high CADR ratings.
Here’s a breakdown of some of the most popular brands and their CADR ratings.
Dyson air purifiers CADR rating
With the vast majority of Dyson air purifiers, you’re not even going to get a CADR rating, as they simply don’t quote any CADR score for their products.
Instead, Dyson believes that CADR testing doesn't show the whole picture, and instead has developed their own testing, called POLAR (Point Loading Auto Response), which they claim is much better at showing real-life scenarios.
Some major publications claimed to have tested their range and these are the results.
Note – We haven’t tested these products and we can not be certain they have either!
Dyson Pure Cool TP04: (according to Wirecutter)
Dyson Pure Cool Link TP02: (according to Consumer Reports)
Dyson Pure Hot+Cool HP04 (according to Wirecutter)
Honeywell air purifiers CADR rating
Honeywell ranges anywhere from 100 to 320, depending on the model and the pollutant type.
Most have a true HEPA filter and are all pretty efficient, though they are designed for different purposes and sizes of spaces.
For example, the Honeywell HPA300 is ideal for rooms of 465 square feet and has a rating of 320 dust, 300 overall. This is their most popular product, and you can see why when looking at the CADR.
Winix C535 CADR rating
The c535 is definitely the most popular model from Winix. It features an activated carbon filter to reduce VOCs (volatile organic compounds) and for odor removal. It has a CADR rating of:
This is a very high rating, especially from such an affordable brand!
Related article: Air purifiers for removing VOCs
Levoit CADR rating
The Levoit Core 300 and LV-PUR131S are affordable and effective air-cleaning solutions.
Both models feature a true HEPA filter and activated carbon filters, which can capture particles as small as 0.3 microns in size, including smoke, pollen, dust, and other allergens.
In terms of CADR ratings, both the Core 300 and LV-PUR131S have a CADR of 135 for smoke, 140 for pollen, and 145 for dust.
These ratings indicate that both models are suitable for use in small to medium-sized living spaces, up to approximately 219 square feet.
Related article: Air purifiers with washable filters
FAQs
Is a higher CADR better?
A higher CADR is generally better. The higher the CADR rating scale, the more effective the CADR air purifier is at cleaning indoor air. However, there are other factors to play into a purifier’s effectiveness.
What does “AHAM Verified CADR” mean?
AHAM-verified CADR means the CADR rating was verified by The American Household Appliance Manufacturers (AHAM). If the purifier has an AHAM CADR rating, you know that it’s a real and reputable rating.
Is CADR the same as CFM?
The CADR and CFM are not the same. CFM stands for cubic feet per minute. CADR does measure the airflow (CFM) times the efficiency of the air filter. For example, if an air filter sports 200 cfm and 100% efficiency, the CADR of that model would be 200.
Is it good to sleep with an air purifier on?
It is good to sleep with an air purifier on. While you’re sleeping, the air purifier will take care of impurities in the air, reducing odors, irritations, and more. Some people also sleep better with the white noise it produces.
How accurate are CADR ratings?
CADR ratings are incredibly accurate. This is because of the very controlled testing environment with not much room for variation.
Is filter efficiency more important than high CADR?
Filtration and CADR ratings ultimately come down to what the user needs. People with severe allergies or respiratory conditions may prioritize better filtration, while those living in areas with high pollution levels or smoke may prioritize a higher airflow rate.
Do purifiers with high CADR ratings have higher energy consumption?
Air purifiers with high CADR ratings tend to have higher energy consumption. They require more powerful motors and higher fan speeds to move larger volumes of air.
