CADR is one of the most misunderstood technical ratings on air cleaning devices.

But it doesn’t have to be.

In this post, you’ll learn exactly what is CADR rating and how it applies to air cleaners.

We’ll also explain how to read a CADR rating scale and the basics behind what is a good CADR rating on an air purifier. That way, you can be well informed on every aspect of the CADR meaning when you’re shopping for and comparing air purifiers to purchase.

What is CADR Rating?

What is CADR rating

CADR stands for Clean Air Delivery Rate. A CADR rating is a certified measurement that reflects an air purifier’s efficacy. CADR ratings measure the volume of air in CFM (cubic feet per minute) with separate scores for tobacco smoke, pollen, and dust.

The purpose of a CADR air purifier rating is to give you an objective standard to evaluate the effectiveness of an air purification device. Therefore, the Clean Air Delivery Rate is the most important metric you need when comparing air purifiers as it relates to the speed and efficiency of an air purifier unit.

If you visit our top air purifiers page, you’ll see individual CADR ratings for the best air purifiers on the market.

See all of Amazon's Best Selling Air Purifiers

What is a Good CADR Rating?

A good CADR rating is equal to at least two-thirds of the room’s area. For example, a room that measures 10 feet by 15 feet has an area of 150 square feet. Therefore, a good CADR rating for an air purifier would be a smoke CADR of at least 100.

Is Higher CADR Better?

A higher CADR rating is better because the higher test numbers indicate a better efficiency at cleaning indoor air. An air purifier with a high CADR rating of 300 for dust will reduce dust particles at a faster rate than a unit with a lower 200 CADR rating.

According to the AHAM, “Using an air cleaner with a higher CADR in that room will simply clean the air more often and faster. If your ceilings are higher than 8 feet, an air cleaner rated for a larger room will be necessary.” The AHAM (Association of Home Appliance Manufacturers) is the organization that oversees the CADR rating program.

CADR Rating Scale

CADR Rating Scale

The CADR rating scale goes up to 400-450 depending on the particle size measured. The CADR scale for dust is 0-400, while the CADR scale for smoke and pollen is 0-450. The CADR measurement gives a relative indication of air cleaning performance for particular room size.

A typical CADR scale for an air purifier would contain three sets of numbers that are separated by a forward slash, such as 350/300/325. In this instance, the 350 would refer to the smoke CADR rating while the 300 is for dust, and 325 is for pollen.

For reference, here are the typical sizes for each type of particle measured along with the CADR rating scales:

  • Smoke CADR Scale: 0-400 (Particles between 0.9 and 1.0 μm)
  • Dust CADR Scale: 0-450 (Particles between 0.5 and 3 μm)
  • Pollen CADR Scale: 0-450 (Particles between 5 and 11 μm)

Note: Particles in the air are measured in micrometer (μm), with one micrometer being one-millionth of a meter, or 1/25,400th of an inch.

Is CADR the Same as CFM?

CADR is not the same as CFM but they work together. CADR is derived from CFM by multiplying the cubic feet per minute by the efficiency of the air filter. For example, if an air filter has 300 CFM and 75% efficiency, then the CADR is 225.

How is CADR Calculated?

CADR is calculated by putting an air purifier in a room measuring 1,008 cubic feet. The air purifier runs for 25 minutes and the levels of the three contaminants are measured against the pre-test levels. This test provides a calculated CADR rating for dust, pollen, and smoke particles.

The ANSI/AHAM AC-1-2006 reports, “The 1008 ft3 test chamber size is an integral part of the definition and is standardized in ANSI/AHAM AC-1-2006 to ensure that comparisons between units that have been evaluated using the standard are fairly made. This standardized room size chamber limits the maximum CADR measurement (or value) to 450 (pollen and smoke) and 400 (dust). These maximum CADR values were determined through analysis of the acceptable minimum number of available particles, an average background natural decay rate (from statistical study), the size of the chamber, and the available minimum experiment time.”

What is AHAM Verified?

AHAM verified means that an air purifier has been independently tested by the Association of Home Appliance Manufacturers. AHAM is the verification agency that oversees the CADR rating program and reports energy, volume, and certain performance criteria for air cleaning devices.

CADR Rating Summary

We hope you enjoyed this comprehensive guide on the topic of “What is CADR rating?”

As you learned, the CADR meaning is for Clean Air Delivery Rate, and this measurement takes into account the efficiency of an air purifier to remove three types of particles: smoke, dust, and pollen. And the CADR rating scale is 0-400 for smoke and 0-450 for dust and pollen.

In regards to what is a good CADR rating on an air purifier, you want the measurements for each score to be at least two-thirds the size of the room area in square feet. For example, a Clean Air Delivery Rate for smoke in a room that is 500 square feet in size would be 330 CADR. If the air purifier had a CADR rating of 320 or less, then the unit would not be considered as efficient.

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About David Morrison

David is an Air Quality & Comfort Technician. He has expert knowledge on the technology and design of air purification, air conditioning, and heating systems. His main role is to write content that helps people get the most value out of their air purifiers, air conditioners, and heating units. (See Full Bio)