Air purifier quick picks
Air purifier for up to 100 square feet: Honeywell HEPA-Type Tabletop Air Purifier
Air purifier for up to 150 square feet: Blue Air Pure 511
Air purifier for up to 250 square feet: Coway Airmega AP-1512HH Mighty
Air purifier for up to 500 square feet: Winix 9800 Air Purifier
Air purifier for up to 750 square feet: Medify MA-112 Air Purifier
Shopping for the best air purifier for your home can get quite technical, quite fast. There are acronyms all over the place. AHAM, HEPA, CADR — the list goes on. And when you just want to make an informed purchase to ensure the appliance you’re buying is actually cleaning the air by removing unwanted particles, all those terms can get a little overwhelming.
Don’t worry, no average person should be an expert on air cleaners. That’s why we consulted the people who are — civil engineers, allergists and air-filtration lifers — to help us explain. With their guidance, as well as some hands-on testing of an air purifier that checks nearly every box, we have everything you need to know when buying one yourself.
Best air purifier: Coway Airmega AP-1512HH Mighty
For spaces up to 348 square feet, you can’t go wrong with Coway’s Airmega Mighty. Not only is it an effective HEPA air cleaner with a built-in air quality monitor but it’s made to last. We’ve used ours for more than two years nonstop, and it hasn’t malfunctioned once.
Even though it’s been running nonstop for two years, I rarely think about my Airmega Mighty. That’s what sets this model apart from other air cleaners: It blends in with its surroundings and is reliable, easy to use and not the least bit finicky. Sure, there’s some maintenance involved like cleaning the pre-filter and air-quality sensor and replacing its two filters, but those tasks range from monthly to annually.
Otherwise, it just hums in the background, adjusting its fan speed (while on Auto mode) based on how polluted the air is. Though we weren’t able to measure air quality directly in our testing, the Mighty excelled at sucking in dust, smoke and other harmful particulates and blowing out clean(er) air. That’s also apparent on paper, where the Mighty fulfills most of our experts’ criteria.
To start, the Mighty features a high-efficiency particulate air (HEPA) filter that removes at least 99.7% of airborne particles with a size of 0.3 microns or more, including dust, pollen, mold and bacteria. Replacing these filters on the Mighty can be expensive at around $50 a pop, but HEPA filters are essential to an effective air purifier, as explained in the section below.
A sufficient Clean Air Delivery Rate (CADR) — the volume of filtered air that a cleaner delivers — is also crucial. While a higher CADR is generally better, it’s more important that you match your air purifier’s CADR to room size. With a CADR in the low-to-mid 200s, the Mighty should be effective in rooms as large as 348 square feet. (Below, we explain how to calculate this yourself.) The California Air Resources Board (CARB) has also certified the Mighty, testing it for electrical safety and ozone emissions.
In the eyes of air purification experts, the only way the Mighty might fall short is its inclusion of an ionizer, which emits ozone, an odorless gas that irritates the lungs. Put simply, extra air-cleaning technologies, such as ionizers and ultraviolet disinfectors, often do more harm than good and should be avoided. Luckily, you can leave the Mighty’s ionizer off, which leaves you with a dependable, time-tested HEPA air cleaner that will work in all but the largest rooms.
How to choose an air purifier
Your choices are seemingly infinite, so knowing how to choose an air purifier is key. These aren’t one-size-fits-all machines, but there’s plenty of direction available to make sure you end up with an air purifier that does its job.
Certification from AHAM and CARB
One easy way to determine if an air cleaner is worth buying is to look for third-party certifications. Dr. Shelly Miller, an indoor air pollution expert and professor at the University of Colorado, Boulder, recommends consumers buy devices tested by the California Air Resources Board (CARB) and the Association of Home Appliance Manufacturers (AHAM).
CARB-certified devices have been tested for electrical safety and ozone emissions, a requirement for all air cleaners sold in California. Meanwhile, AHAM focuses on performance, verifying models’ CADR through testing at an independent lab.
We recommend starting with AHAM’s robust directory of certified air cleaners, as you can easily search for “AHAM Verified” products by CADR, room size and more.
Clearly reported CADR and ACH
Clean Air Delivery Rate (CADR) measures the volume of clean air a given machine delivers. While we’ll get into the right amount of CADR you need, it’s important to ensure the air purifier you’re buying is upfront about its CADR. Models that don’t disclose CADR are often not worth considering.
Knowing your unit’s CADR can help you determine how many air changes per hour (ACH) it’s capable of, or how many times all the air in a space is cleaned. The bigger the room, the more airflow you need to clean all the air in it. “You’d need a smaller air cleaner for a bathroom than you would for a living room with 14-foot ceilings,” says Jim Rosenthal, former president of the National Air Filtration Association and co-creator of the DIY Corsi-Rosenthal air cleaners. Why? Because whatever is in the air that requires cleaning isn’t going to suddenly stop.
“Particle generation is dynamic,” Rosenthal says. “In other words, if you’ve got somebody in the room and they’ve got COVID, they’re breathing. And because you clean the air once an hour, that doesn’t mean you’re going to protect anybody, because they’re constantly emitting particles. Wildfire smoke constantly goes through the walls and cracks and into your house. It’s not like you eliminated it and it’s gone forever.”
The goal, Rosenthal says, is typically between four and six ACH. As long as your CADR is measured in the standard cubic feet per minute, you can easily calculate ACH by multiplying your machines’ CADR by 60 and dividing that number by the room’s volume, which is its square footage multiplied by its height.
Follow the 2/3 rule
When we spoke to experts, they repeatedly stressed the importance of picking an air purifier that’s sized appropriately. “Air cleaners are not magic,” says Dr. Jeffrey Siegel, an indoor air quality (IAQ) expert and the Bahen/Tanenbaum Chair in Civil Engineering at the University of Toronto. “They work well if sized properly, maintained, used appropriately and are part of a larger IAQ management strategy.”
So, how do you know if an air purifier is efficient enough for your space?
AHAM follows the 2/3 rule, which states that the CADR of your air cleaner should be at least 2/3 of your room’s area. Say, for instance, you have a 150-square-foot bedroom. To calculate the required CADR, you’d multiply square footage (150) by 2/3, which gives you a minimum CADR of 100.
Since manufacturers typically list CADRs for different particles, we recommend picking the lowest number for your calculations to be on the safe side. If you hate math and don’t want to deal with the 2/3 rule, you can use AHAM’s directory, which lists the maximum room size for each device.
But don’t trust manufacturers to furnish accurate maximum room sizes, as many companies exaggerate their numbers. Coway, for instance, says its Airmega Mighty provides 1,748 square feet of coverage, while the 2/3 rule dictates that it only works in rooms up to 348 square feet (for pollen). Again, this is why it’s crucial to look for third-party certifications and testing.
HEPA filters are only half the battle
You’ll see these four letters everywhere when shopping for an air purifier. For filtration, HEPA stands for high-efficiency particulate air. HEPA filters are a widely accessible gold standard in the industry because they’re “effective in extracting and capturing tiny particles, including smoke,?allergens, airway irritants from the air, thereby reducing their presence in your home,” says Schweiger Dermatology Group allergist Dr. Clifford W. Bassett.
But while HEPA filters are effective and reliable, any old air purifier won’t necessarily do its job solely because it’s outfitted with a HEPA filter. The filtration is only part of the equation. “That’s why you want to focus on clean air delivery rate,” Rosenthal says. “Because [CADR] doesn’t care what the filter is. What it’s doing is telling you how much clean air is delivered … If the airflow is 100 feet a minute, there won’t be nearly enough cleaning to clean a bedroom or any room of a reasonable size. You gotta have … enough power.”
Avoid unproven features and gimmicks
Ozone generation. Ultraviolet light. Ionizers. If these terms sound like scientific breakthroughs designed to transform your home into a breathing paradise of perfect air, think again. They’re not. They instead are gimmick features that don’t have enough scientific backing to sway your purchase decision. If they can be turned off, like the ionizer in the Coway Airmega, that’s great. But if they’re permanent features, you’re better off looking elsewhere in your search.
Something like ozone, a smog that irritates the lungs, “may be more harmful than helpful,” says Dr. Karen Dannemiller, principal investigator of Ohio State University’s Indoor Environmental Quality Research Group.
Or take UV light, which needs three conditions to kill bacteria, Rosenthal says. “It needs proximity, it needs dwell time and it needs intensity. Your proximity is there. … But you have no dwell time. It’s going at 500 feet a minute. There’s not enough time for the UV to do anything. I’ve always considered it to be an unnecessary add-on.”
Affordable replacement filters and energy efficiency
If an air purifier satisfies the above criteria, you can be sure it’ll clean your air. But for an excellent model, you’ll want to consider how much it’ll cost you over time. Siegel says filter replacements will be the most expensive long-term expense, so you’ll want to see how much they cost before settling on a device.
You should compare air cleaners’ energy efficiency too. Like AHAM and CARB, Energy Star has a database of models that meet its efficiency standards, with the best appliances receiving the Energy Star Most Efficient badge. To give you an idea of how much this can vary, the air purifier with the lowest yearly energy consumption in the database uses around 35 kilowatts a year, which would cost you just over $6 at the time of publication (using the US Bureau of Labor Statistics data). The Coway Mighty? Around $81 a year.
Other great air purifiers we recommend
For rooms up to 100 square feet
Though it lacks an air-quality sensor, Honeywell’s AHAM-, CARB- and Energy Star-approved tabletop model earns plaudits for its small size, which makes it perfect for a bedside table or desk. Plus, filter replacements cost under $20.
A loud air cleaner is no good because you’ll never want to turn it on. Clean Air Kits, which Rosenthal himself has used, uses PC fans to up the craftsmanship and turn down the noise of a Corsi-Rosenthal box. Their smallest unit makes five air changes per hour in rooms up to 138 square feet.
For rooms up to 150 square feet
With only three fan speeds (and not much else), this small but mighty device has few features. And yet, it’s a steal at its current price, especially since it uses a HEPA filter and has earned approval from CARB, AHAM and Energy Star.
When wildfires in Canada brought blankets of smoke to New York City in 2023, Bassett said he and his team relied on Rabbit Air devices to clean their air. This CARB- and Energy Star-certified model comes with a pricey upfront cost, but you’ll benefit from a robust five-year warranty, long-lasting filters and a layer of carbon pellets for odor control.
For rooms up to 250 square feet
This simple design from Bissell, which is certified by AHAM and CARB, won’t be an eyesore while cleaning up everything you can’t see in rooms up to 363 square feet. It has a HEPA filter and an additional layer of carbon filtration for odors, plus a clearly displayed air-quality monitor.
Suitable for spaces up to 360 square feet, this energy-efficient, AHAM-approved air cleaner boasts a full-featured control panel, including an air-quality monitor, Auto mode and timer.
For rooms up to 500 square feet
No matter how you look at it, this air purifier is impressive. It has all the certifications we recommend, a HEPA filter and tons of premium features, including an app that lets you control it from a distance. Despite those goodies, it’s still affordable, priced at around $50 more than the Coway Mighty.
Without known CADR figures, which Austin Air doesn’t provide, it’s hard to justify the price of this model. But Rosenthal told us he’s used it for years because its filtration system includes a hefty amount of carbon and zeolite to remove odors effectively.
For rooms up to 750 square feet
One of the largest cleaners certified by AHAM, this CARB- and Energy Star-approved beast is great for larger rooms and is AHAM-graded as suitable for up to 921 square feet. While it does come with UV light and an ozone-free ionizer, those features can be turned off.
Suitable for rooms up to 801 square feet, the AeraMax SV is AHAM- and CABR- approved and Energy Star-certified. It’s more powerful than needed for a small room, but large apartments or entire floors of a house would benefit from its no-gimmick cleaning.
