Air Purifier CFM (What Does It Measure?)

Do you want to learn about air purifier CFM ratings?

CFM is a crucial measurement of the air flow strength of a portable air purifier.

In this guide, I will go over...

  • Exactly what is CFM?
  • How CFM is different than CADR
  • Picking the right CFM

Let's get started with this guide!

air purifier CFM

What is Air Purifier CFM?

The CFM of portable air purifiers is a measurement of their strength or capacity. CFM stands for cubic feet per minute, and this number tells you how much volume of air an air purifier can filter.

The average home air purifier will be able to move in the 100-400 cubic feet per minute of air. Larger air purifiers will have bigger CFMs (such as 300-cfm or more) and will be able to handle larger volume rooms.

Smaller air purifiers will have lower CFMs (such as 100-cfm or less) and will be suitable for small rooms or desktops.

Read Also: What Are The Best Quiet HEPA Air Purifiers?

How To Pick The Best CFM?

Before choosing an air purifier simply based on CFM, you may want to determine how many air changes you want per hour for a particular room.

If the air purifier is for a basement or bedroom, 3-4 air changes/hour is probably sufficient.

If you want an air purifier for a higher use room such as a kitchen or laundry area, you may want to go more in the 7-9 air changes per hour range. Anything more than this range of 3-9 air changes is more suitable for high use commercial rooms such as public bathrooms.

Read Also: Where Should I Place My Air Purifier?

Formula To Get Desired CFM

Once you have determied the desired number of air changes (based on the room), then you simply multiply this number by 60-min and divide it by the volume of the room to give you the CFM required.

The minutes cancels out in this equation.

(Air Changes Per Hour  X  60-min)  /  volume of room =  CFM

Now that you have the CFM you need for that room based on the number of air changes, you can choose accordingly. You can pick one air purifier that meets that CFM or exceeds it — or you can buy 2-3 air purifiers that total the desired CFM.

Read Also: What Are The Best Large Room Air Purifiers?

air purifier cfm (1)

What Is CADR?

CFM is also an important factor in determining the CADR or clean air delivery rate.

The CADR is a standardized measurement of the efficiency of an air purifier, and these ratings are given by the Association of Home Appliance Manufacturers.

To get a CADR value, you multiply the CFM of the air purifier by the amount of particles that it can remove of a particular size. You will get three different CADRs based on whether it's for smoke, dust, or pollen. 

Or in other words, CADR is the CFM that is required to remove a standardized amount of particles in a 1,008 cubic foot room. So in essence, CADR is a number you get when you combine the air flow of an air purifier (CFM) and the particle removal efficiency.

The CADR is important because you may be tricked into buying an air purifier with a high CFM rating, but in reality it has very poor filtering abilities. Just because an air purifier has a high CFM, it doesn't doesn't always mean it filters well.

Read Also: How To Clean The Oreck XL Professional Air Purifier?

Final Thoughts

Choosing the right air purifier can be a challenge, but knowing the desired CFM is a great place to start.

All you have to do is first decide how many total air changes you want per hour for that particular room (usually in the 4-8 range). And then you multiply this number by 60 and then divide it by the room volume. Voila... you have the required CFM for the room.

But if you want to go farther than just CFM, you can look at the CADR values of that air purifier. CADR is an efficiency measurement that takes into account the CFM and the particle removal efficiency.

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Arie Van Tuijl

Arie Van Tuijl

Arie is the founder of Home Inspector Secrets, an online resource dedicated to helping people understand how homes work. He is a licensed home inspector in two U.S states and owns a residential and commercial inspection company (read his full bio on the About page). To ask Arie a question, please use the comment box at the bottom of the relevant article.

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Home Inspector Secrets is an online resource for owners, buyers, and sellers to understand all aspects of home maintenance. We have detailed home guides, product reviews, inspection advice, and much more.