The Best Air Purifier

Breathe a little easier
The 30-Second Review

When it comes to air purifiers, CADR is king. CADR is the rating assigned by the Association of Home Appliance Manufacturers, and it tells you what size room the best air purifiers can, well, purify. We tested out eight that were rated to clean close to 360 square feet of pollen, dust, and tobacco smoke, then spoke with air quality specialists and physicians about the importance of true HEPA filters and other features before landing on our two top picks.

Best Overall

Excellent clean-air ratings, slick looks, and killer bells and whistles at budget prices make this an easy top pick.

A Close Runner-Up

Equally lightweight, quiet, and effective as our top pick. If you prefer the looks of the Coway, it's a great choice.

  • December 13, 2017 — We’ve updated our review to assess a total of 85 air purifiers, up from 45 when we first published. Air purifiers from two new brands — Electrolux and Kenmore — met our specifications, but after trying them out for ourselves, our hearts still belong to the Winix and the Coway. Of all our finalists, they continue to offer the best balance of competitive CADR ratings, reasonable pricing, and intuitive design.

The 2 Best Overall Air Purifiers

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Left: Our top pick, the Winix 5500-2 Air Cleaner. Right: the bubblier Coway 4-Stage Filtration System.

Pop quiz: What’s dirtier — the air inside your home or the air outside of it? According to studies conducted by the Environmental Protection Agency (EPA), the air inside a home might be two to five times more contaminated with pollutants, be it animal dander, cigarette smoke, or soot.

Enter the air purifier. They can be hugely beneficial for allergy and asthma sufferers, as well as anyone who lives near major highways or other pollutant-filled areas, like coal plants. The best ones use fans to cycle air through a series of filters, capturing impurities and jetting clean air back into the room. Choosing the right one comes down to its CADR rating — the measurement for how well an air purifier actually works. Aside from that, the right type of filter — a true HEPA is key — and making it sure it can accommodate the size of room you want will have you breathing easy.

The Winix 5500-2 Air Cleaner is our top pick due to impressive CADR ratings and slightly better construction than our runner-up. It’s powerful enough to cover 360 square feet, about the size of an average master bedroom (although it’ll work just as well in smaller spaces). The Winix can clean the air in a room up to four and a half times per hour — exceeding the minimum four times recommended by experts. It has an easy to replace True HEPA filter plus intuitive controls. Manufacturer pricing is $250, but we’ve consistently seen it listed on Amazon for $135 over the past year.

The Coway 4-Stage Filtration System came incredibly close to taking our top spot. Like the Winix, it has top-tier CADR ratings and can cover up to 360 square feet. It’s slightly more powerful, capable of cleaning the air in a room five times per hour. But the filters are a little more difficult to replace, and the Coway tends to be more expensive, typically retailing for $230. It’s a great choice for those who like it’s bubbly design or during the rare occasion when the Winix isn’t available.

Our Seven Finalists and Their CADR Ratings

Max Square Footage

CADR Pollen Score

CADR Dust Score

CADR Tobacco Smoke Score

Air Exchanges per Hour

Winix 5500-2 (Top Pick)
Coway 4-Stage Filtration System (Runner-Up)
GermGuardian® AC9200WCA
Winix True HEPA U450 Air Cleaner
Honeywell HPA300
Electrolux EL500AZ
Kenmore 83396

Our Picks for the Best Air Purifier

Our Top Pick

Winix 5500-2 Air Cleaner with PlasmaWave Technology It was nearly a tie with our runner-up, but this air purifier is cheaper up front and boasts better construction.

For a reasonable balance between price and performance, our frontrunners were the Winix and the Coway. The other five systems we considered sometimes had slightly better technical specs, but these tiny increases in coverage equalled hundreds of additional dollars upfront, often for machines that were bulky or counterintuitive to use.

We preferred the Winix, finding it a little easier to use and a little cheaper than the Coway. But honestly, they’re so similar that choosing between them comes mostly down to aesthetics. In terms of performance, both have nearly identical pre-filters, true HEPA filters as their primary purifiers, and some sort of charcoal filter to absorb odor. (The Winix has little pockets of charcoal nubs; the Coway has charcoal foam, like what you get in your kitchen compost bin, or on top of a litter box.)


The Coway (top) has a nearly identical filtering system as the Winix (bottom).

The Winix 5500-2 technically has lower CADR ratings than the Coway, but the difference is incredibly small — for smoke the Winix has a rating of 232 and the Coway has a rating of 233 — but the Winix is typically priced at least $50 cheaper than the Coway. (We’ve seen it retail for nearly $100 less on Amazon and Home Depot.) Rather than focus on negligible differences, we like the Winix because it excels at cleaning our air and provides a better value.

Other than price, the differences between our top two picks boils down to looks and maintenance — and even those are nit-picky. We prefer the matte charcoal Winix to the glossy Coway, which was a magnet for cat hair and dust. And even though the Coway is cuter in an alien-TV sort of way, the taller, slimmer Winix ended up a more discreet room addition. (The same could not be said for large units like the Winix U450 or Electrolux. The Winix U450 was a bit too bulky for our taste, while the Electrolux’s high setting was so loud it made our tester feel like they were riding an airplane.)

Popping the hood of the Winix was easy. The cover uses magnets to snap in and out of place, and each filter locks inside the next — there’s no question where each piece should be when you’re taking it apart and then putting it back together to replace the filters. The Coway is much flimsier, and it takes a couple of tries to put the front and pre-filter back on after you remove them. It’s not a deal breaker, but if you’re taking it apart every two weeks to rinse out the pre-filter (which is recommended for both units), the Coway is more of a hassle.

How did other models compare? Put simply, none could compete with the Winix 5500-2. Even the other Winix model that we tested, the larger U450, was less impressive, with a filter design we found less intuitive to replace. And replacing the filters for the Kenmore and Honeywell forced our tester to consult the manual multiple times. The front panel for the Kenmore had a tendency to stick when being opened or closed, leaving our tester worried about breaking it.

As for extra features, the Winix 5500-2 touts bamboozling proprietary PlasmaWave Technology, which, when activated, claims to “instantly neutralize airborne viruses, bacteria, chemical vapors, odors, and gases” (!!!). It also produces positive ions which avoids the “grounding of junk” that standard ionizers suffer from. We didn’t really take this particular piece of marketing seriously — in fact, if it had jacked up the price, we likely would have skipped recommending the Winix altogether. But it didn’t, and the unit offers more useful features like intuitive controls and a built-in air quality sensor that decreases the speed setting to save power when the air quality is good. The Winix also has timers and sensors that measure air purity, with glowing LED lights that shift from blue to red the more polluted the air. On its Auto setting, the Winix will automatically runs the fan at its lowest when the air quality is good — a nice touch for saving power. (Although even here, the Coway offers similar features.)

Admittedly, there are more powerful air purifiers on the market. The Winix U450 ($440) has higher CADR ratings, but you’re only paying for an additional 100 feet of square coverage, plus a pre-filter treated with something called “Antimicrobial CleanCell Protection,” which is supposed to help reduce the development of bacteria, fungi, and mold. We’re not convinced. If you’re worried about bacteria, we think you’re better off putting two Winix 5500-2 units in opposite corners to make up for the square footage and using the leftover cash to stock up on hand sanitizer. The Winix U450 is a nice alternative if you must have a single purifier or the most powerful unit available. But the Winix 5500-2 is our top choice for having impressive CADR ratings and affordable price which makes it a breath of fresh air in the complicated world of air purifiers.

A Very Close Runner-Up

Coway 4-Stage Filtration System with Air Quality Indicator A more petite purifier also rated for 360 sq. feet, and with the cheapest filters we saw. Long-term, this one is the better deal.

The Coway 4-stage Filtration System is also an impressive model. If it weren’t for the higher price and the greater hassle with swapping filters, it would likely be our top pick.

The Coway is a touch better than the Winix in terms of CADR ratings for smoke and dust (although slightly worse at capturing pollen), and it also excels in number of air changes per hour. At the max setting, the Coway averages five air changes for a 360 square foot room with a nine foot ceiling — the average ceiling height of a home. The Winix only averages four and a half air changes. But like CADR ratings, the difference is small, and both numbers exceed the minimum recommendation by our experts.

Another bonus is that the Coway has cheap replacement filters. In the long term, the costs of the Coway will eventually turn into savings. If you use it for at least five years, it will theoretically average out to be cheaper than the Winix. (We calculate the full annual cost of running each machine below). The Coway is an excellent air purifier that won’t disappoint in the off-chance that the Winix isn’t available, or if you just prefer the Coway’s aesthetic.

Did You Know?

For long-term costs, factor in replacement filters and energy use.

Air purifiers aren’t a one-and-done purchase — replacement filters and energy use will affect your bottom line, especially considering that air purifiers are typically left on all the time to do their thing. Figuring out the long-term cost out takes some fast math.

To predict your electric bill, you need to know how many kilowatt-hours your purifier uses per day, multiplied by the average electricity rate where you live. Let’s use our top pick as an example: The Winix 5500-2 runs at 70W, or 1.68kWh. Denver electricity runs is 11.05 cents per kilowatt-hour. To run the Winix 5500-2 all day every day for a year, you’re looking at about $68 a year added to your electric bill.

Replacement filters are less complicated. The Winix HEPA filter is about $80 a pop; the Coway is closer to $50, and you replace each about once a year. (Replacement secondary filters are included with each machine’s replacement HEPA filter.)

Winix 5500-2

Coway 4-Stage Filtration System

Upfront Cost
Replacement HEPA Filter
Cost to Run for 1 Year (Denver)
Total After 1 Year
Total After 5 Years

Because the Coway’s HEPA filters are such a good deal, the costs after a year are nearly negligible between our two top picks. After five years, the Coway may end up costing you less.

Placement is key.

Make sure your air purifier isn’t flush against walls or furniture, as most units work best when they can take in air from all sides. In a bedroom, situate the purifier roughly 6 to 10 feet from your bed (specifically, the headboard), with the registers facing you — this should help facilitate the flow of clean air toward you while you sleep.

“Air purifiers are especially critical during the sleeping hours when lung function naturally decreases, making the airways more susceptible to irritant inflammation.”

In addition, the closer you sit to your air purifier, the cleaner the air will be. Wu explained that “usually, if you sit closer to the air purifier, you’ll get a gradient of clean air that’s better. Over time, as long as it’s in an enclosed space, it’ll average out.”

You can improve the quality of your air even without an air purifier.

A purifier can help mitigate pollutants in the air, but it won’t cure your allergies or rid your home of pet hair. It’s worth it to develop a few good habits to help keep airborne irritants out of the home.

Vacuum your floors frequently.

Carpets hold lots of dust, pollen, and other irritating particles. (In fact, for people with who asthma or allergies, living without carpet is the best option.) But vacuuming can help improve air quality, especially if you use a vacuum with a HEPA filter. As with air purifiers, this filtration system helps ensure that the dust particles sucked up by the vacuum don’t escape back into the air. Two of the vacuum models that we tested and liked when we reviewed Best Vacuums use HEPA filtration systems and are good for both carpeting and hardwood.

Check the outdoor air quality, and if it’s good, open your windows to let fresh air in.

Ray Wu told us that “if the air is good outside, open your window. It can improve the health of your environment. Air purifiers don’t generate oxygen or remove carbon dioxide; that’s why you want some fresh air.” His advice was to look online at weather channels to check for the outdoor air quality. In addition, if you live near a bunch of traffic or in a city, he advised not to open windows during peak traffic. Instead, Wu says to “wait for when there are less cars so you don’t pick up that pollution.”

Bathe your pets regularly.

Pet dander is especially tough to manage, because it doesn’t stay airborne for long, often settling into carpets and onto walls and furniture before an air purifier has time to capture it. Keep dander at bay with regular bathing and brushing — and plenty of vacuuming. Feel your allergies flaring up at night? It might be worth it to keep those pets out of the bed while you sleep. (We know. Easier said than done.)

Strive to keep your home’s humidity around 30–50 percent, which helps keep mold in check.

You can use a hygrometer to measure humidity levels, but there’s a simple way to do a quick check: If there’s fog and condensation on your windows, your home’s humidity level is probably too high and you may need to invest in a dehumidifier.

Ask your guests remove their shoes before coming inside.

It’s probably not a surprise, but shoes are dirty. They can track in harmful bacteria, dust, and other debris that can affect the air quality of your home — not to mention give you more to vacuum. Leaving shoes at the door prevents these risks.

Don’t smoke or allow smoking inside your home.

The jury is in and has been for a while: Smoke is bad for your lungs and the air quality of your home. Smoking outside or not at all helps ensure your indoor air quality stays clean.

If you use a space heater during the winter, give it a good cleaning every few months.

Have you ever smelled something burning when you plug in your space heater during the first cold snap of the year? Chances are that smell is burning dust, which tends to accumulate on the surface guards of heaters. Giving your space heater a clean before use can help prevent the spread of dust as well as that bad smell. (In the market for a new space heater? Check out our favorites.)

CADR ratings are the best measurement for performance, but aren’t without flaws.

While CADR ratings give the most accurate representation of an air purifier’s ability to actually purify air, this testing method isn’t perfect. It doesn’t do anything to measure gaseous pollutants or very small particles (anything below the 0.3 micron threshold that HEPA filters are able to catch). Plus, they only include results for the purifier on its highest setting.

That said, CADR ratings are currently the best option available, and these results are trusted by organizations like the EPA and Consumers Union. We’ll keep an eye out for new testing procedures, but in the meantime, CADR remains the best way to gauge which air purifiers are the real deal.

The Best Air Purifier, Summed Up