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    Air Purifier Room Size - How to Know Square Footage
    Click:920 Date:2020-04-28 08:49:00 Information Source:

    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

    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.


    For most situations you will want somewhere between 2 and 5 air changes per hour. In other words, to clean the air every 12 to 30 minutes in a room.

    If you have smoke, severe allergies, asthma or COPD we suggest you stick with 5 air changes per hour to get enough air flow to keep the air in your room very clean.

    Finally, 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. 

    How to Measure the Square Foot Area of Your Room

    When I first wrote this content about room size and square footage I did not include a section on how to measure a room. It seemed so simple but after thinking about the implications in choosing the right air purifier, there are some key points to make.

    Of course, 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.