Air Purifier Room Size – Your Guide To Knowing Square Footage

A room-size air purifier is the perfect solution to improving the quality of your indoor air. No doubt you will  spend time online reviewing air purifiers with the best quality HEPA filters to ensure you choose the right one for your needs. One of the most important factors to consider is air purifier square footage. Simply put, this is the way to determine that the air purifier coverage area does not exceed the capability of the air purifier.

An air purifier cannot filter allergens, viruses, and unpleasant odors if it is not sized correctly for the space. In this guide, we discuss the benefits of using an air purifier and how to make sure you select the correct model for the job.

Benefits of a room air purifier

Everyone knows air pollution is harmful to their  health. But did you know the air quality inside your home can be unhealthier than the air outside? Fortunately, an air filter that’s  the correct room size can literally help clear the air. When you choose an air purifier that’s suitable for your room coverage area, you can enjoy the following health benefits:

  • Fewer allergy and asthma symptoms. Reducing indoor allergy and asthma triggers  such as  mold, pollen, dander, and dust can help make breathing indoors easier. A quality HEPA air filter can help.
  • Reduction of harmful chemicals. Closing windows and doors is not a guarantee that harmful chemicals will stay outdoors. Some pollutants such as carbon monoxide and nitrogen dioxide can seep inside your home and make breathing difficult if you don't have an air purifier.
  • Removal of unpleasant odors. Strange odors can be found inside homes, especially if they are not well ventilated. However, opening windows can trigger allergies or asthma symptoms. Using an air purifier to rid your home of unpleasant odors is a better option.
  • Lessened chances of airborne diseases. If you live with other family members then you know the drill. One person sneezes and then you all start sneezing. The good news is, air purifiers are excellent at combating airborne viruses that lead to illness.
  • Improved sleep. When indoor allergens trigger allergy or asthma symptoms, sleeping can be difficult due to a stuffy, runny nose or shallow breathing. Running an air filter that is room size can help you get a better night’s sleep .

Air Purifier Room Size - How to Know Square Footage

A key part of choosing a top air purifier is making sure it can fully clean all of the air in your room.

In this guide we will give you the information you need to determine how much square footage your air filtration system will clean.

Need help choosing the right air cleaner? Check out our help me choose guide. In 3 simple steps we find the best air purifier for you.

CADR (Clean Air Delivery Rate)

Having a high efficiency filter and one that lasts without a drop in performance is great. But you also need to move the air.

The CADR rating is way to measure the amount of clean air flow that comes out of the air purifier. This was developed by AHAM (Association of Home Appliance Manufacturers). The Clean Air Delivery Rate (CADR) is the industry standard for measuring the air flow of filtered air.

AHAM is a leader in setting the room air purifier standards in the US. This covers both air filtration performance and noise level. They have a program called AHAM Verifide. The purpose of the program is to help consumers know what they are buying since each air cleaner in the program has verified results.

They do this by secretly testing air cleaners from brands in the program. Air purifiers are tested at the Intertek air purifier lab in New York under strict guidelines. The Clean Air Delivery Rate results are reported on the AHAM web site. This way you know exactly what you are getting.

Oransi is a member of the AHAM Verifide program. Sadly, some heavily marketed brands do not participate so it's unclear what their performance is since they are not tested to the standard. In many cases it is not even reported.


The advantage of the CADR ratings for air purifiers is you know the units have been tested in a certified test lab to the industry standard. Intertek/AHAM also helps manage the Energy Star program.

It's a great place to start in assessing an air purifier's sq ft coverage.

While the CADR Rating is a good metric in our opinion it has some flaws in our opinion. It's good in that it represents the filtered air flow. So, you know it can clean the square footage for a room size.

There are a few issues with the rating. One is it does not measure the air filter performance over time. Two, it is only based on removing airborne particles sized 0.3 microns and larger. This represents dust and larger particulates. It does not measure the smaller particles and gases. These smaller airborne particles make up 90% of all particulates and cause most health issues.

So, if you have the best true HEPA air filter on the market you do not get credit in removing the smallest particles since they are not part of the test. The use of higher efficient filters also adds air flow resistance. So, the air flow will be lower than an air filter with lower efficiency (HEPA-type filter).

We know this going in and to provide you with the best air filters without sacrificing air flow, we make our filters larger and use top notch motors.

In 5 reasons to buy Oransi we explain how we give you the best air filters available and do it in a way that is also quiet and covers a large room size.

How to Know Room Sq Ft Coverage For an Air Purifier

It's hard to know how much square footage an air purifier can clean other than what a brand tells you. To help you understand how to compare products we put together this handy guide so you can see how many square feet of coverage to expect for a given CADR.

The specifications of many air purifiers on the market just give a room coverage number but fail to give you all of the information to know exactly what to expect.

The numbers below the Air Changes per Hour columns show the square footage for each CADR rating. In addition, we include the corresponding Oransi air purifiers so you can see how they compare.

Sq Ft Coverage Based on Clean Air Delivery Rate

Determining air purifier coverage for the square footage of your room 

Once you have the square footage of your room, it will be easier to determine the air purifier coverage area and select a purifier that can adequately service the space. Here is where the process gets a bit trickier, as you must rely on the specifications provided by air purification system manufacturers. Some brands give a “room coverage” number that can be subjective.

Using the Clean Air Delivery Rate (CADR) is a better solution. CADR measures the amount of clean air flow coming from the air purifier. Developed by the Association of Home Appliance Manufacturers (AHAM), CADR  the industry standard for measuring the airflow of filtered air. This guide can help clarify what you can expect from a room-size air purifier.

Ideally, you should select an air purifier that offers between 2 to 5 air changes per hour. With this rating, you can be assured your air purifier is cleaning the air every 12 to 30 minutes. For homes with pets or smokers, go for the maximum of 5 air changes per hour to significantly reduce the number of allergens.

Getting an Air Purifier based off CADR

Since the CADR is based on the highest fan speed you may run the air purifier on a lower fan speed. When you do this the room coverage will also decrease. So, if you can swing it you will be better off getting a more powerful air purifier than you think you might need. This is why we made the EJ and Erik650A air purifiers. They coverage very large room sizes and you can dial down the fan speed so it is silent and you still get the square footage coverage for your room.

How to measure the square footage of your room

Now that you know the value of owning a room-size air purifier, the next logical question is, “What size air purifier do I need?” The size of the air purifier depends on the overall dimensions of the room. Smaller rooms need less filtration than larger rooms, so it’s  important to have accurate measurements before you begin shopping for an air purifier.

Calculating the area of a room is simple. It requires a measuring tape and accuracy. We recommend recruiting a  partner who can assist in taking and ensuring the measurements are accurate. Once you have a measuring tape and a willing assistant, measure the length and width of your room in feet and then multiply the two numbers to get the square footage of the room.

To calculate square footage you measure the length and width of your room in feet. Then multiply the two numbers to get the square footage.

In using the CADR rating to determine whether an air purifier can clean the size of your room is pretty straightforward using the table above.

However, you need to be aware that these numbers are based on a ceiling height of 8 ft. If your ceiling height is higher then the square foot coverage of the air cleaning device will be less than shown.

The CADR rating indicates the volume of air through the air purifier filters in cubic feet per minute. So, it's not enough to only consider the room size based on the square foot area if your ceilings are higher.

For example, if your room is 100 sq ft and the ceilings are 8 ft high, the volume of air in your room is 800 cubic feet. With 10 ft high ceilings, your room size is 1,000 cubic feet. Or 25% more.

In this case you will need to reduce the values in the table above by 25%. This can make a big difference in the amount of air flow you need from the air purifier.

Learn More

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