Loud air purifiers are a bother. Nobody really likes that 60+ dB constant noise just because we want to breathe cleaner air. We are talking about air pollution vs noise pollution here. It is no surprise that everybody prefers quiet air purifiers for bedrooms, for example. Obviously, getting the quietest air purifier would be the best choice for sleeping.
Most air purifiers produce more than 60 dB of noise output when running at full speed. Picking an air purifier without looking at the noise levels is one of the most common mistakes (and you have to listen to all that noise). Quiet air purifiers are very rare and hard to find but the quietest air purifiers can generate even less than 50 dB.
We rounded up 4 of the best whisper-quiet air purifiers, based on their super silent operation and overall specification.
Here’s the thing:
Despite the lack of a compressor, air purifiers are usually as loud as portable or window AC units. Two primary sources of noise are:
- Fan motor. Brushed air purifier fan motors can produce quite a lot of noise. That’s why the quietest air purifiers will use brushless fan motors.
- Airflow (CFM) through HEPA filters. Airflow through HEPA filters – essential for capturing air particulates – produce a pressure drop. Pressure drop is always connected with increased noise output.
The super quiet air purifiers reduce either fan motor noises (Example: Using BLDC motor used by #3 RabbitAir MinusA2 SPA-780A) or use special noise-reducing HEPA filters (Example: Super quiet H13 HEPASilent filters used by #1 BlueAir Protect 7470i).
On top of that, the best quiet air purifiers should also have a high enough CADR rating (200+ CFM), be energy efficient (run on less than 100W), be visually appealing, not cost $1,000, and last for at least 5-10 years or more.
Based on these specs, we have created a list of the 4 quietest air purifiers currently on the market, complete with a spec-by-spec analysis and individual reviews. You can check the complete list further on.
First of all, however, it is important that we understand the key air purifier specs we should check out before buying one of these quiet air purifiers. Let’s go through them one by one:
5 Key Specs Vital For A Quiet Air Purifier
Needless to say, noise levels at low, medium, and high fan speed settings are important here. However, these are not the only metrics we want to check even with the quietest air purifiers.
Here is a list of key factors that we should consider when opting for a silent air purifier:
- Noise levels. We should focus not on the lowest fan speed setting (those are usually below 40 dB we can hardly hear that), but on the maximum noise levels.
- CADR rating. This is usually a #1 spec for selecting air purifiers in general. It tells you how well an air purifier can remove dust, smoke particles, and pollen from indoor air. The CADR rating is independently measured by AHAM and gives us a key insight into the quality of filtration we can expect from air purifier filters (mainly HEPA filters).
- CADR per dB. This is a key metric measuring the ratio of air purifier performance (CADR rating) and its noise output (decibels).
- Coverage at 4.8 ACH. The smallest air purifiers are usually the quietest, but they have an adequately high CADR rating to service standard or bigger rooms. Based on the 2 ACH to 4.8 ACH calculation (ACH = Air Changes per Hours), we can see how big a space these super quiet air purifiers can cover.
- Energy efficiency. As we have written in our article about air purifier running costs here, running a 100W+ air purifier for 24h can cost more than $0.50 per day. To reduce electricity costs, we should aim for 80W max. wattage or less.
Let’s first check the noise levels:
1. Air Purifier Noise Levels (dB)
“This air purifier produces less than 27 dB of noise.”
You may see something like this in the description of the air purifier you are looking at. Be mindful that these kinds of sentences are written by marketing people, not engineers. More often than not, they just highlight the noise levels at the lowest fan speed (or even at ‘Sleep’ mode).
The important thing is to open the specification sheet and check the highest dB rating (at max. fan speed).
Example: Medify MA-125 is one of the best air purifiers for dust on the market. It produces only 33 dB noise levels. Sounds quiet, right? That’s the low fan speed. If you check the max. noise levels in the specs sheet, it actually produces deafening 67 dB noise levels at the highest fan speed setting.
Here are rough benchmark dB ratings for air purifiers (running at 100% output):
- Max. noise levels above 70 dB: Loud air purifier.
- Max. noise levels between 65 dB and 70 dB: Above-average loud air purifier.
- Max. noise levels between 60 dB and 65 dB: Standard air purifier noise output.
- Max. noise levels between 55 dB and 60 dB: Quiet air purifier.
- Max. noise levels between 50 dB and 55 dB: Super quiet air purifier.
- Max. noise levels below 50 dB: Quietest air purifier.
If you are looking for a quieter air purifier, just check that the max. dB levels are not above 60 dB. There are only two of the top quietest air purifiers on the market that can run at below 50 dB noise levels (#1 BlueAir Protect 7470i and #2 Alen BreatheSmart 75i in the list below).
2. CADR Rating (Filter Quality)
The first thing to check whenever selecting any air purifiers is the CADR rating. When looking for the quietest air purifiers, the noise levels are the most important but CADR rating is obviously very important as well.
CADR stands for Clean Air Delivery Rate. It is a measurement AHAM (Association of Home Appliance Manufacturers) makes to see how well air purifiers remove indoor air particulates (dust, smoke particles, and pollen) and thereby improve indoor air quality (IAQ).
CADR ratings range anywhere from 30 CFM to over 400 CFM. If you are going for a quiet air purifier, however, you should know that higher CADR ratings are associated with higher noise levels. That’s because, in order to produce a high CADR CFM rating, the fan motor has to work extra hard to penetrate fine fiber HEPA filters.
Quiet air purifiers will seek a compromise between CADR rating and noise levels. With the implementation of quiet running fan motors and noise-reducing HEPA filters, we can get more than 200 CFM at below 50 dB noise levels (this is the engineering threshold with today’s filtration and motor tech).
In order to adequately increase indoor air quality, you should aim for a quiet air purifier with at least 200 CFM.
Here is how we can look at this performance vs noise compromise:
3. CADR Rating Per Decibel (Sound Performance Of Air Purifiers)
On the specs sheets, you will find both CADR rating and noise levels. To see how well air purifiers reduce indoor air pollutants (denoted by CADR rating) while keeping the noise levels low (dB rating), you can calculate the ratio between these two.
Example: #2 Alen BreatheSmart 75i has the highest CADR per dB ratio. It generates only 49 dB noise levels while performing at a 347 CFM CADR rating. Here is how we can calculate air purifier sound performance:
Sound Performance = CADR Rating / Noise Levels
With Alen BreatheSmart 75i, this calculation looks like this:
Sound Performance = 347 CFM / 49 dB = 7.08 CFM/dB
That means that the Alen air purifier will be able to produce more than 7 CFM of clean air for every decibel point. This is the highest and the best noise-performance ratio of any air purifier on the market.
The quietest air purifiers can produce 5 CFM or more clean air output per dB. If you see a 3 CFM per dB ratio or below, you either know you are dealing with a loud good-performance air purifier or a quiet bad-performance air purifier.
In short, aim for at least 5 CFM/dB if you want an air purifier that has both a silent operation and good performance.
4. Coverage Area (For Quiet Operation)
When buying any air purifier, you should know how big a space you want to put it in. Air purifiers can cover areas as little as 100 sq ft and as big as 1000 sq ft. This may sound a bit paradoxical but if you want a quiet air purifier you should go with a bit of an oversize unit.
Here is why:
Bigger air purifiers are, in general, louder. However, you don’t have to run them at the highest fan speed setting. Here is a little trick for choosing a quieter air purifier:
A big air purifier running on ‘Low’ setting will often produce much less noise than running a small air purifier on ‘High’ setting.
That’s because bigger air purifiers have larger HEPA filters and the fan motor needs to produce less airflow to achieve the same CADR rating.
Be aware that the maximum coverage space is usually calculated for 2 ACH or 2 Air Changes per Hour (all the air being replaced every 30 minutes). That’s why you will see these big 1,000+ sq ft numbers.
IAQ researchers at Harvard, however, recommend at least 3 ACH for better ventilation. On top of that, AHAM measures and calculates the coverage area to 4.8 ACH (the new standard). That’s why you will see in the table below that all air purifiers have a coverage area calculated with 4.8 ACH in mind.
Even at 4.8 ACH, the best quiet air purifier can have 400 sq ft or more coverage. If you see coverage with 300 sq ft or below, be careful: These are smaller air purifiers you will have to run at the highest fan speed setting that generates the most noise.
General recommendation: If possible, go for 400 sq ft at 4.8 ACH coverage area to ensure quiet operation. This will also enable you to run the air purifier at a lower less noisy fan speed setting.
5. Energy Efficiency (Below 100W)
How much electricity will an air purifier spent is not as important as noise levels and CADR rating. Nonetheless, quiet efficient air purifiers are better than quiet inefficient air purifiers.
Just be mindful that the highest wattage doesn’t exceed 100 watts. If you run a 100W air purifier at 100% output for a whole day, it will spend 2.4 kWh of electricity, costing about $0.30 to $0.60 per day. That can be more than $10 per month or $120 per year.
In the comparison table below, you will see that all of the quietest air purifiers on the market run on less than 70W. The difference between running a 100W and 50W air purifier can be anywhere between $20 and $100 per year.
With all this in mind, let’s finally have a look at the best quietest air purifiers currently on the market:
Best Quiet Air Purifiers (Comparison Table + Reviews)
1. Quietest Air Purifier On The Market: BlueAir Protect 7470i
|Maximum Noise Levels:||45 dB|
|Lowest Noise Levels:||22 dB|
|CADR Rating:||275 CFM|
|CADR Per 1 dB:||6.11 CFM/dB|
|Silent Tech:||HEPASilent Ultra Tech|
|Coverage (At 4.8 ACH):||418 Sq Ft|
|Power:||8 – 48 Watts|
|Dimensions (W×L×H):||11.8 × 11.8 × 27.2 Inches|
BlueAir Protect 7470i is the absolute quietest air purifier on the market. Their focus is on the best quiet H13 HEPA filters that significantly reduce noise levels while maximizing air filtration performance.
These are HEPASilent dual filters, patented by BlueAir (they are of Swedish design). To reduce the noise levels, a dual mechanism of electrostatic charging and mechanical filtration is implemented. That requires a lower pressure drop across BlueAir Protect 7470i HEPA filters; that means that the fan motor doesn’t have to work so hard and thereby ensures a quiet operation.
How quiet exactly?
At the lowest fan speed setting, BlueAir Protect 7470i produces only 22 dB of noise (operating at 8W input). At the highest fan speed setting, the noise levels stay under 50 dB which is almost unheard of. Even when running at 100% output, the BlueAir Protect 7470i will produce merely 45 dB of noise (operating at 48W input). That’s a record-setting lowest dB rating for an air purifier.
Filteration is superb. BlueAir doesn’t use ordinary H10-H12 HEPA filters. Their HEPASilent filters are rated as H13 or medical-grade filters. That means they are capable of removing more than 99.97% of airborne particulates like dust, smoke particles, pollen, mold spores, pet dander, and so on, which is down to 0.1 micron in diameter.
For comparison, H10-H12 HEPA filters can adequately capture 0.3-micron particles but will struggle to keep the efficiency for 0.1 micron sized particles. Because these very small 0.1 micron particles can cause allergies, the BlueAir Protect 7470i is the best quiet air purifier for allergies such as asthma.
Despite whisper quiet operation, the BlueAir Protect 7470i is capable of achieving a 275 CFM CADR rating (280 CFM pollen CADR, 275 CFM dust CADR, and 270 CFM smoke CADR). This means that it has a very high performance vs noise level ratio (6.11 CFM/dB, to be exact).
It is a big room air purifier that can cover about 1000 sq ft at 2 ACH. At AHAM-measured and recommended for allergy-prone people at 4.8 ACH, the coverage area is 418 sq ft (given 8 ft ceiling height). That means that you don’t have to run it at top speed in most rooms; you can run it on a low or medium fan speed setting which makes the BlueAir Protect 7470i run even more quietly.
Obviously, these new HEPASilent filters are not cheap and the unit costs about $800. It is also taller than most air purifiers in order to store these quiet HEPA filters.
All in all, BlueAir used a lot of smart engineering (including the IAQ sensors, app, and so on) to create the world’s quietest air purifier. It run at incredibly low noise levels, is energy efficient, big enough to cover any room (or several of them), and uses the advanced medical-grade H13 HEPASilent filters:
2. Extremely Quiet High CADR Below 50 dB Air Purifier: Alen BreatheSmart 75i
|Maximum Noise Levels:||49 dB|
|Lowest Noise Levels:||25 dB|
|CADR Rating:||347 CFM|
|CADR Per 1 dB:||7.08 CFM/dB|
|Silent Tech:||Pink Noise Generation|
|Coverage (At 4.8 ACH):||542 Sq Ft|
|Power:||1.5 – 45 Watts|
|Dimensions (W×L×H):||12 × 19 × 15.6 Inches|
Alen BreatheSmart 75i is one of the two air purifiers (besides BlueAir Protect) capable of operating at below 50 dB noise levels even at 100% running speed. On top of that, it has an exceptionally high CADR rating and the highest noise performance of all air purifiers on the market.
Alen BreatheSmart series is quite legendary as the first air purifier series tested (by SleepScore Labs) on how well air purifiers improve sleeping. The combination of breathing very clean air (thanks to H13 HEPA filters) and the must-have requisite of low noise levels showed that ‘participants reported falling asleep faster and felt more rested the next day’.
At the lowest fan speed setting, Alen BreatheSmart 75i produces only 25 dB of noise (running on 1.5W input). As we have explained, the highest noise level specs are more important: When running at full speed, this air purifier will produce only 49 dB of noise output (running on 45W input). That makes it one of the quietest air purifiers.
Similar to BlueAir Protect, Alen BreatheSmart 75i also use advanced medical-grade H13 HEPA filters for thorough air pollutant removal. These superb H13 HEPA filters are capable of capturing more than 99.97% of air pollutants with a size of 0.1 microns in diameter.
The best thing about Alen BreatheSmart 75i, besides the whisper quiet operation, is the very high 347 CFM CADR rating. That means it can produce 7.08 CFM of clean air delivery rate (CADR) per every decibel point. This means that the Alen BreatheSmart 75i has the best compromise between performance and noise levels.
Due to high CADR rating, Alen BreatheSmart 75i has a very high 542 sq ft coverage area at 4.8 ACH. Needless to say (you’ve seen the wattage), it has a very low running cost. With 45W producing 347 CFM CADR rating it even has the Energy Star label.
All these quiet air purifiers tend to be more expensive; this is the case with Alen as well. The filters also have an above-average price because they are H13 HEPA filters that are much more effective than standard HEPA filters (those are, of course, cheaper).
In short, your ears will be soothed by the incredibly low noise levels Alen BreatheSmart 75i produces. With such a high CADR rating (and best in industry noise-performance), you can run it on low or medium setting, thereby reducing the noise levels even further:
3. Very Quiet Air Purifier With Great Track Record: RabbitAir MinusA2 SPA-780A
|Maximum Noise Levels:||51.3 dB|
|Lowest Noise Levels:||25.6 dB|
|CADR Rating:||191 CFM|
|CADR Per 1 dB:||3.72 CFM/dB|
|Silent Tech:||Brushless BLDC Motor|
|Coverage (At 4.8 ACH):||340 Sq Ft|
|Power:||7 – 61 Watts|
|Dimensions (W×L×H):||20× 7 × 21.4 Inches|
Before the BlueAir introduced the HEPASilent filters and Alen BreatheSmart series, the RabbitAir MinusA2 SPA-780A was all the rage as far as quiet air purifiers go. RabbitAir uses an ultra silent fan motor to reduce the noise levels significantly. It is still one of the best-selling quiet air purifiers.
Almost all air purifiers are loud because they use brushed fan motors. RabbitAir, on the other hand, uses a brushless BLDC motor to run the fan. This quiet motor produces at most 51.3 dB of noise, making the whole air purifier extremely silent compared to standard-noise units.
The caveat of this motor is that is not all that powerful. It produces a 191 CFM CADR rating which is still above the average but it cannot compare to the bigger fans that the two under 50 dB air purifiers we checked prior to this have. This also reduces the noise performance to 3.72 CFM/dB.
RabbitAir MinusA2 SPA-780A has its advantages, however: It is the quietest wall-mounted air purifier. That means that you don’t have to put it somewhere on the ground where it would take away your square footage.
At 4.8 ACH, it has a 340 sq ft effective coverage space.
All in all, RabbitAir MinusA2 SPA-780A is still one of the best-selling quiet air purifiers because it already has a good track record and can be mounted on the wall but it falls a bit short in the CADR rating department:
4. High CADR Rated Quiet Air Purifier: Coway Airmega 400
|Maximum Noise Levels:||52 dB|
|Lowest Noise Levels:||22 dB|
|CADR Rating:||352 CFM|
|CADR Per 1 dB:||6.77 CFM/dB|
|Coverage (At 4.8 ACH):||650 Sq Ft|
|Power:||Up To 66 Watts|
|Dimensions (W×L×H):||14.8 × 14.8 × 22.8 Inches|
Coway Airmega 400 is another quiet air purifier. Coway is quite a reputable brand and the Airmega 400 has the highest CADR rating for a below 55 dB air purifier.
At a low-speed setting, it produces 22 dB of noise output. At the high fan speed setting, it produces 52 decibels (with a 66W input). It doesn’t have any particularly patented technology that reduces noise levels.
As you can see, it has a very high noise-performance ratio (6.77 CFM/dB). This is because it has such a high 352 CFM CADR rating for a 52 dB air purifier.
Due to this high CADR rating, it has a 4.8 ACH coverage space of 650 sq ft. In most cases, you will use it in smaller places. That means that you can run it at a lower fan speed setting that will produce even less noise output.
It is, however, a bit bulky (14.8 × 14.8 × 22.8 inches dimensions) and it uses 66W when running at full speed.
All in all, Coway is another good choice for a silent air purifier, a one with the highest CADR rating and a superb noise-performance:
This has been a general overview of what to look for when buying quiet air purifiers. The list of the quietest air purifiers on the market will help you made an adequate and a silent enough choice for your home.