What is a Good CADR Rating for Air Purifier

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When purchasing an air purifier, the most important metric you need to check is the Clear Air Delivery Rate, popularly referred to as CADR. CADR is the highest standard for measuring air purity, created by the Association of Home Appliance Manufacturers (AHAM).

Although this rating is one of the most misunderstood ratings, it is quite simple and easy to understand. Below, we are going to take a look at the answer to the question “what is a good CADR rating for air purifier”. Let’s get to it.

What is CADR?

The Clean Air Delivery Rate is a certified measurement that generally reflects the efficacy of an air purifier, and it typically measures three types of particles and pollutants. These particles are pollen, dust, and smoke, and the metrics are given in those three categories. Smoke, dust, and pollen represent small, medium, and large-sized particles, respectively, which an efficient air purifier should eliminate from the air.

In the United States, the CADR rating measures the volume of air in cubic feet per minute. In other parts of Asia and Europe, it is measured in cubic meters per minute or cubic meters per hour. Manufacturers are not required to list the rating of air purifiers. Doing this is voluntary, so you can never be sure if an air purifier will have a CADR rating. An air purifier with a high CADR rating is generally fast at cleaning indoor air pollutants.

How is it Calculated?

Two factors influence the rating scale: air flowing through the filters and the filter’s efficiency. The CADR rating measures the efficacy of an air purifier in moving airflow in cubic feet per minute multiplied by the efficiency of the air filter. 

Together, they indicate how much air can be filtered from the purification system. For example, a purifier running at 200 CFM with a filter efficiency rate of 75% would have a CADR score of 150. 

Smoke, Dust, and Pollen CADR Scores

Clean Air Delivery Rate scores are in three main categories: pollen, dust, and smoke. The measurements indicate how much of these pollutants the air purifier eliminates from indoor air. 

  • CADR scores of smoke. Smoke particles are considered to be the tiniest particles that an air purifier can remove from the air. They are very fine particles and are between 0.1 and 0.3 microns.
  • CADR scores of dust. Particles in this category are medium-sized and are the most frequently filtered particles. They have a size of 0.5 to 3 microns. 
  • CADR scores of pollen. Pollen particles are the largest and can be easily seen by everyone. They represent particles like pet hair and pet dander. The size of these particles falls between 5 and 11 microns.

CADR Scale and How the Ratings are Helpful

While shopping for an air purifier, you should get one that is AHAM verified. A purifier verified by the AHAM is one that they have independently tested. Depending on the size of the particle measured, the Clean Air Delivery Rate scale may go as high as 400 to 450. Dust CADR may measure up to 400. Pollen and smoke CADR can go up to 450. The score gives a performance indication used to determine how much of the room the air purifier covers.

CADR ratings give a reliable score on the performance of the air purifier. The scores are individually tested and can be trusted. Determining the CADR rating is also a great way to measure the unit’s strength and to know if the purifier has the capacity to clean indoor air thoroughly.

Maximizing the CADR Rating

Regardless of what the CADR rating of your air purifier is, you can still get the most out of it. Follow these easy steps to maximize the CADR rating of your air purifier:

Use it at the highest speed

Running your air purifier at the highest speed it can go is one way to maximize its efficiency. When the air purifier is allowed to run at the highest speed, you maximize the rating while also maximizing the overall effectiveness. You also need to find out the pre-filter used in the air purifier. The pre-filter is responsible for capturing large particles like pet hair and pet dander before clogging the main air filter.

 Continuously run it

Constantly running your air purifier will not damage it. Modern systems were built with the mind that users would constantly use them. Running your air purifier every hour of the day will increase its CADR rating. It will have no adverse effect on the unit, so don’t be afraid of letting it run continuously. Follow the manufacturer’s suggestions and replace all the air filters that need to be replaced. Leaving an air filter in when you should replace it can result in ugly situations. 

Close all windows and doors

While operating the air purifier, ensure that all windows in the room and doors leading to the room are closed. The Clean Air Delivery Rate will significantly diminish if the unit has a high amount of outdoor air to go through. Leaving windows and doors open will reduce the efficiency of the air purifier. To maximize the CADR rating, ensure outdoor air stays outside.

Woman touching touchscreen checking air purifier filter

What CADR Rating is Good for Your Air Purifier

Clean Air Delivery Rate tests are usually done in a sealed-off chamber of 1,008 cubic feet. The conditions in the chamber are not the same as the conditions a typical user would experience. To get the CADR of your air purifier, you may have to calculate a little. You need to determine if the CADR of the air purifier is good enough for the size of your room. It’s important to note that the score is not always flat.

The Association of Home Appliance Manufacturers (AHAM) has an easy formula for determining what CADR range the purifier you want to utilize should have. Multiply the CADR score by 1.55. If you know the size of your room, take the square footage and divide it by 1.55. The result will give you a rating suitable for your room.  

For example, you have a room of 260 square feet. Dividing it by 1.55 will give you a score of 168. This means that to get the most efficiency from your purifier, you should get one with a CADR score of 168 or higher. The AHAM has suggested using the “two-thirds rule” when trying to determine what CADR rating is good for you. The rule says that an air purifier has an appropriate CADR rating if the score is two-thirds of the maximum airflow measured in cubic feet per minute (CFM).

For example, you see a purifier with a maximum airflow of 210 CFM, but you have no idea the CADR rating. Following the two-thirds rule, you can determine what two-thirds of 210 is. Hence, the CADR rating would be 140 CFM. 

Final Thoughts

Knowing the CADR rating good for an air purifier isn’t as difficult as some may think. An easy way to determine the CADR rating you need is by using the two-thirds rule. If you do not know what the maximum airflow is, use the square feet of your room to know what CADR rating is good for you. Once you’ve figured out what CADR rating is good, ensure you do your best to maximize the rating. 

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