Looking for a bedroom-sized air purifier? Alright, whenever we are picking an air purifier for bedroom, we need to think about 2 key factors:
- Size. The air purifier has to be adequately sized for the bedroom’s square footage. The capacity of an air purifier to capture air particulates is expressed in CADR rating. We need to match this CADR rating with our bedroom square footage and our desired ACH (usually 2 or 5 Air Changes per Hour; more about that later on).
- Noise levels. In the bedroom, you want an air purifier that is silent enough for sleeping. It makes no sense to pick an adequately sized air purifier with 60 dB noise levels and put it in the bedroom; nobody can sleep with that “jet engine” next to your head. We will show you a trick to reduce air purifier’s noise levels in bedrooms.
To help you pick the right size air purifier for a bedroom, we created a Bedroom Air Purifier Size Calculator you can freely use (if you know all about ACHs and “get a bigger unit for bedroom, run it on lower speed” we are going to cover now, you can jump directly to the calculator here).
Before we check out the calculator (with Bedroom Air Purifier Size Chart), let’s first talk about the sizes of bedrooms and explain what ACH is (because it matters a lot):
Bedroom Sizes (Sq Ft)
Here is a chart of bedroom sizes from Measurement Of:
| Square Footage: | Master Bedroom: | Kids Bedroom: | Guest Bedroom: |
| Small | 180 – 224 sq ft | Below 120 sq ft | Below 100 sq ft |
| Standard | 224 – 350 sq ft | 120 – 196 sq ft | 100 – 150 sq ft |
| Large | 350 – 420 sq ft | 196 – 306 sq ft | 150 – 200 sq ft |
The job of an air purifier is to clean all the air in the bedroom. Here is where the ACH or Air Changes per Hour comes in:
- For standard clean air, we use 2 ACH. That means that all the air in the bedroom is purified 2 times per hour (every 30 minutes).
- For the cleanest air (recommended for allergy-prone people), we use 5 ACH. That means that all the air in the bedroom is purified 5 times per hour (every 12 minutes).
Example: Standard-sized master bedroom (224 – 350 sq ft) will need an air purifier with a 60 to 93 CFM CADR rating at 2 ACH. At 5 ACH, we will need an air purifier with a 149 to 233 CFM CADR rating for the cleanest possible air.
Key Insight For Bedroom Air Purifiers (Useful Tip)
Now, before we check the calculator, here is the main tip for all bedroom air purifiers:
If you calculate you need, say, a 150 CFM CADR-rated air purifier for your bedroom, don’t pick a unit with a 150 CADR rating at max. speed. Pick one with, say, 250 CADR rating at max. speed.
Why is this?
Because you want to run a bedroom air purifier at low or medium fan speed setting. This is to reduce noise levels enough so you can sleep with an air purifier inside the bedroom.
Here is a quick example: Medify Air MA-50 is one of the best air purifiers you can buy. If you look at the CADR rating by fan speed setting and the corresponding noise levels, you will notice something:
| Fan Speed: | CADR Rating: | Noise Levels: |
| Speed 1: | 19.0 CFM | 21.2 dB |
| Speed 2: | 90.6 CFM | 32.3 dB |
| Speed 3: | 159.5 CFM | 42.7 dB |
| Speed 4: | 352 CFM | 60.6 dB |
Most people can sleep next to an air purifier that produces less than 50 dB noise levels. Almost nobody can fall asleep with a 60+ dB noise levels unit next to their hair.
From the table, we see that you can’t really run Medify MA-50 at max. speed (Speed 4) in the bedroom because it produces 60.6 dB noise levels (yet it does produce the highest 352 CFM capacity).
Rather, when going to sleep, you would rather reduce the speed to Speed 3 or even Speed 2 because they produce only 42.7 dB and 32.3 dB noise levels for a considerable 159.5 CFM and 90.6 CFM CADR rating, respectively.
Key point: For the bedroom, you should buy a bigger air purifier and run it at lower speeds (Speed 2, 3 in this case).
Note: Most unit specs sheets don’t include CADR and dB noise levels at Speeds 1, 2, 3, etc. That’s why we usually divide the max. speed CADR rating by 2 to get to sensible sleeping decibel levels. A 200 CADR-rated air purifier, when put into a bedroom, should run at about 100 CFM CADR speed (at reduced noise levels).
Here is the bedroom air purifier sizing calculator that encompasses all these considerations:
Bedroom Air Purifier Size Calculator
Let’s use this calculator to determine the size of the air purifier for a 14×16 bedroom (with a standard 8 ft ceiling height) just to illustrate how to use the calculator.
We insert ’14’ ft bedroom width, ’16’ ft length, and slide the ceiling height to ‘8’ ft. Here is the result we get and interpretation (screenshot):
We see that for a standard 14×16 bedroom, we would need air purifiers with the following capacities (expressed in CFM CADR rating):
- For 2 ACH (standard clean air), the minimal size is 59.73 CFM. Because we want to run it at low or medium speed when sleeping, we need an air purifier with about 119.47 max. CFM CADR rating.
- For 5 ACH (cleanest air), the minimal size is 149.33 CFM. Since we want to run the unit at low-medium speed, we need an air purifier with about 298.67 CFM CADR rating.
In short, we would need about 120 CADR-rated air purifiers for 2 ACH and about 300 CADR-rated air purifiers for 5 ACH filtration.
You can use the calculator above to calculate these results for your bedroom. We did calculate air purifier sizes in this manner for 100-400 sq ft bedrooms, and summarized the results in this bedroom air purifier size chart:
Bedroom Air Purifier Size Chart
| Bedroom Size (Sq Ft): | Air Purifier Size (2 ACH, Quiet): | Air Purifier Size (5 ACH, Quiet): |
| 50 Sq Ft | 26.67 CFM CADR | 66.67 CFM CADR |
| 100 Sq Ft | 53.33 CFM CADR | 133.33 CFM CADR |
| 150 Sq Ft | 80 CFM CADR | 200 CFM CADR |
| 200 Sq Ft | 106.67 CFM CADR | 266.67 CFM CADR |
| 250 Sq Ft | 133.33 CFM CADR | 333.33 CFM CADR |
| 300 Sq Ft | 160 CFM CADR | 400 CFM CADR |
| 350 Sq Ft | 186.67 CFM CADR | 466.67 CFM CADR |
| 400 Sq Ft | 213.33 CFM CADR | 533.33 CFM CADR |
We hope this makes picking the right size of air purifier for your bedroom (with quiet operation) a bit easier. You can check our all-encompassing air purifier size calculator here.