Understanding the Star Rating of an Air Purifier Before Buying?

Understanding the Star Rating of an Air Purifier

Every product of Air purifier is provided with a rating label on it. The rating label will give the consumer to better understanding the Star Rating of an Air Purifier or a particular product, based on some limitations. 

But many of us are not aware of what this rating label on the product is actually saying. 

If you are all set to buy an air purifier then it’s all about understanding the star rating of an air purifier for the best one.

The best way to understand a star rating label on an air purifier is, the number of stars on it will tell you how effective service it produces with less power consumption. The less energy it consumes means the less will be the electricity bill. 

In this way, we can understand the star rating simply….fine…But how we measure it….

I think you are also here to know about the star rating of an air purifier right!!!

So, let’s get into the details of it.

understanding star rating of an air purifier

How to measure the star rating of an Air Purifier?

Getting deeper into the details of air purifier measurements, CADR, Clean Air Delivery Rate is the way to measure the rating of an air purifier.

CADR is calculated by the amount of clean/ contaminant-free air that is delivered by the air purifier within a space. 

This measurement is to measure first by measuring the areas of the room in square meters. The chart of CADR according to the area of square meters is as follows,

If the room area is 100 sq.ft then the minimum CADR will be 65. Likewise,

  • For 200 sq.ft – 130 CADR
  • 300 sq.ft – 195 CADR
  • 400 sq.ft – 260 CADR
  • 500 sq.ft – 325 CADR
  • 600 sq.ft – 390 CADR

These measurements might vary when we have more than 8 ft ceilings. You may also go for the one with the highest CADR but it will be useless for the fewer areas than specified as it will consume more energy.

But, when it comes to the best performance of an air purifier, it is measured in ratio of CADR to Watts. A certified air purifier will have a minimum of 2.0 CADR/watts ratio.

And also the CADR number of air purifiers indicates the dust particles based on the size from smaller to large. Smoke particles are indicated as smaller particles which are of 0.09 – 1 micron, Dust particles as medium particles which are of 0.5 – 3 microns, Pollen particles as large particles which are of 5 – 11 microns.

Check out the article by click here to more about the air purifiers

Factors that influence the rating scale of Air Purifier

Apart from the above measurements, there are some factors that actually influence the rating scale i.e performance of an air purifier.

Filter efficiency

Along with the rating of an air purifier, it is important to remember the filter efficiency which means the ability to remove the dust/smoke particles from the air, as it plays a key role in air purification. The filters also get change from one air purifier to others. Among all the different types of air purifiers, the HEPA filter is the best. It has the highest filter efficiency of filtering 0.1 micron-sized particles, compare to the other filters, but it cannot remove the smoke particles. So, for this, a carbon activated filter along with HEPA is used to remove the smoke particles.

Power of Fan inside Purifier

A fan fixed inside an air purifier is the main reason for that airflow. The power of a fan is based on how fast the motor in it rotates. The faster the motor rotates, the faster will be the power of a fan to get the airflow of through the filters. It is also indicated by CFM mean cubic feet per minute(in the US) or cubic meter per hour(Asia and Europe).

Noise production

Because of the presence of a fan motor in the air purifier, there are chances for noise production. Though it is not mentioned on the rating label we need to know while purchasing and make sure that noise should not exceed 50 decibels as the noise is measured in decibels dB.


Hoping that now you are able to figure out the star label of air purifier in order to know the best one based on your requirements and the top rating too. Though the air purifier is used to filter the air artificial, it cannot make the air 100% purified. So, try to go for the air purifier option only in the emergency cases. It is to say that natural air is best among all these artificials.

Try to find the ways possible to maintain natural clean and fresh air indoors.

Frequently Asked Questions

Q) Where is the best place to put an air purifier? In general, an air purifier is to be placed 1 or 2 feet away from all sides. But the ideal place is to keep the air purifier is at corners. So, try to purchase the one with front door intake and top side exhaust if you want to place it in a corner.

Q) How do I know my air purifier is working? If an air purifier is working, we can know it by checking the cleanness of filters in it. The working air purifier will have the dust debris on the filters. And dusted filters also says that the filters need to be cleaned. 

Q) Should I leave my air purifier on when I’m not home? No, you don’t actually need to turn it on when you are not home. Generally, it takes 30 min – 2 hours to clean the air in the room. So, you can turn it when you are in-home and during night times for better breathing.

Q) Do air purifiers remove Co2? No, the air purifiers are only manufactured to remove the pollutants from the air with the help of the filter in it. They cannot remove carbon dioxide in the air just by filtration.

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