What is a Clean Air Delivery Rate (CADR) Rating in Air Purifiers?

What is the Clean Air Delivery Rate

A major component that contributes to our health is clean air. However, with the emergence of machines emitting pollutants into the atmosphere, indoor air quality has become a major concern. And air purifiers have been the solution to improve the air quality inside homes and offices.

Anyway, all air purifiers are not created the same way, and choosing one air purifier that does the job well is of utmost importance, this is where the Clean Air Delivery Rate (CADR) comes into play. This article will explain what CADR means, its calculation, and the necessary information one needs to know. Let's carry on.

What is a Clean Air Delivery Rate (CADR) Rating in Air Purifiers?

What is the Clean Air Delivery Rate?

The Clean Air Delivery Rate (CADR) is a standard established and defined by the independent Association of Home Appliance Manufacturers (AHAM) in the U.S. It is certified and verified by an independent laboratory. Moreso, AHAM makes use of CADR to assure consumers that an air purifier will perform according to the manufacturer’s product claims, while also helping shoppers easily identify the air cleaners that work better than others.

How is CADR Calculated?

To calculate CADR, follow the steps below:

Step 1: Measure Room or Space Size (Volume)

This is useful in the sense that, we need to know the quantity of air the purifier needs to clean. To get this, measure the floor in square feet or square meters. Then to get the total volume, multiply this number by the height of the room or space. Let's say the number calculated is in cubic feet, then divide the number by 35 to get the volume of the space in cubic meters.

Step 2: Calculate the CADR needed to Clean the Room

The amount of air a purifier can clean is represented by its CADR rating. Know that, the higher a CADR rating, the more air the purifier can clean per hour.

Calculating the “Power” needed from an air purifier to clean the volume of air calculated in step 1 follows.

Multiply the volume of the space by 3. Once done, the CADR (cubic meters per hour) from a purifier to clean the area) needed is the number after multiplying the volume of the room (in meters cubed) by 3.

The reason “3” is used for multiplication is that most spaces should aim to have all air in the space cleaned 3 times every hour. Hence, an air purifier that is powerful enough to clean this much air is needed.

Step 3: Choose Air Purifier(s) with a CADR Above Number Calculated in Step 2

CADR ratings come in two measurements. One is in cubic meters per hour (CMH) and the other cubic feet per minute (CFM). For the space calculated above, The CADR needed is cubic meters per hour (CMH). Remember that, this can be converted to CMH by multiplying by 1.7, If only the CFM is given.

The range for a CADR of powerful air purifiers is from 500-900 m3/hour. Let's say the CADR needed is over this number, getting multiple air purifiers is the way. For pollen, dust, and smoke, three CADR values are relegated and represent the purifier's adequacy against every molecule type. Higher CADR values show quicker and more proficient air cleansing.

  1. To calculate the value of "Air Purification Efficiency" the formula is "CADR average value" or "single CADR value" ÷ certification applicable area × 100%
  2. The CADR value will be used to mark the air purifiers of regular manufacturers (how much clean air each hour), and the applicable region = CADR×0.12 (0.12 is the conversion factor).

What is a Good CADR?

With dust, smoke, and pollen each having their own AHAM CADR rating, the maximum CADR rating for dust is 400, while for others is 450. However, keep in mind that certain manufacturers may award a higher CADR rating than the maximum based on other test procedures or extrapolation from the AHAM CADR testing. Nevertheless, you need an affordable CADR number that is high enough, but ensure you aren’t overpowering the unit for the space.

What is a Good CADR

To purify the air in a space or a room, an air purifier needs to do two things which are; removing harmful particles and gases, and circulating most of the air in the room multiple times per hour with a fan. As a result, you’ll need to choose a device that does these jobs well. How do you do this?

Getting the right air purifier for your space requires you to calculate your room's square footage by multiplying its width and length. Then, look for a CADR rating that is about two-thirds of that number. According to EPA’s recommendation of five air changes per hour, a minimum CADR rating of 65 is for a 100-square-foot room (with 8-foot ceilings) and a minimum CADR rating of 390 is for a 600-square-foot room (with 8-foot ceilings).

CADR Ratings Explained

The CADR (Clean Air Delivery Rate) Rating system is referred to as a benchmark used to quantify an air purifier's viability in eliminating contamination/pollutants from a room. It helps to tell how much clean air a purifier conveys per minute. These CADR ratings are explicit mathematical values, however, no single range applies generally. Hence, the most extreme CADR rating depends on certain factors like the pollutant type being estimated. Here is a breakdown:

  • Smoke CADR:This rating centers around fine particles around 0.09-1.0 microns, which include tobacco smoke and a few allergens. The ordinary range goes from low (around 50) to high (around 450). A higher smoke CADR shows improved effectiveness at eliminating smoke and comparatively measured contamination.
  • Dust CADR:The dust rating targets medium-sized particles (0.5-3 microns). Some examples are dust mites, mold spores, and pet dander. The range is like smoke CADR, with values from low (around 50) to high (around 400). Know that a higher dust CADR implies better evacuation of these normal household allergens.
  • Pollen CADR:This rating deals with bigger particles (5-11 microns). Examples are pollen, hair, and some dust. The range is normally low (around 50) to high (around 450). Know that a higher pollen CADR demonstrates better viability against sensitivities to pollen set off by dust.

Advantages of a High CADR

Choosing a high CADR rating has a lot of advantages, some of which are ensuring effective cleaning of air pollutants, such as dust, pollen, smoke, and other airborne particles. Likewise, a higher CADR rating means that the air purifier can rid the air of contaminants faster, hence making it more efficient.

How CADR is Tested

Testing CADR involves measuring an air purifier's effectiveness in ridding the environment of pollutants. A breakdown of the general processes includes:

How CADR is Tested


  • Test Chamber:The air purifier is set in a fixed chamber with a particular volume, normally around 30 cubic meters.
  • Introducing Pollutant:Pollutants like smoke, dust, or particles with a certain size distribution in controllable amounts are brought into the chamber.
  • Mixing and Background Measurement:Mixing guarantees even contamination appropriation inside the chamber. Afterward, baseline pollutant levels are estimated after representing natural settling.


  • Air purifier Actuation:The air purifier is turned on at its most extreme fan speed.
  • Toxin Decrease Checking:Throughout a set time (generally 20 minutes), the reduction in contamination concentration is ceaselessly observed.

What is a CADR Rating in Air Purifiers?

CADR stands for “Clean Air Delivery Rate.” The CADR metric is a measure of how clean the air volume a purifier can provide in a fixed amount of time and space – mostly a measure of the purification rate at maximum fan speed. The amount of filtered air that passes through a purifier is measured – in any case, it ought not to be an independent measurement to evaluate the full presentation of modern-day smart purifiers.

How to Choose the Right Air Purifier Based on CADR

Choosing the right air purifier requires comprehension of certain things. The CADR which measures how quickly a unit delivers filtered air can also be used to measure the performance of a room air cleaner. In essence, know that the higher the CADR, the wider the area the air cleaner can serve. Hence, the utmost importance is needed to select a room air cleaner specific to your room size. A rule generally used is considering the “2/3 rule” – i.e., finding an air cleaner with a CADR that is at least 2/3 the square footage of the space.

Additional Considerations When Choosing an Air Purifier

Quiet Operation: Low Noise

In this case, Air purifiers with acceptable noise levels should be selected for uninterrupted operation, especially if they need to run continuously.

One thing is, the noise level of an air purifier can affect your comfort, especially in bedrooms which are supposed to be quiet spaces. Hence, necessitating the need for a model with a low noise level, ideally under 55 decibels.

Wattage and Fan Speed

The wattage and fan speed influence air purifier electricity consumption and are regarded as a critical factor. With higher wattage and fan speed comes faster air cleaning, which may lead to increased energy use. Therefore, choose settings that match your air quality needs.

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