7 best air purifiers for large rooms we have tested

Not any air purifier will do to clean large rooms — we look at high CADR, smart functions and budget units
By
Updated on June 26, 2024
Written by
Teddy Booth
Teddy was a senior content producer for HouseFresh between 2019 and 2024 producing written content as well as product photography. He supported Danny as a product tester and lead how-to writer.

Our verdict

  • My top recommendation for large rooms is the Levoit EverestAir for its high-performance cleaning power and extra features in a stylish design.

 

  • If a quiet environment is essential, I recommend the Smart Air Blast Mini, as this enormous air purifier only emits 49 dB at its highest fan speed.

 

  • If you’re looking for more bang for your buck, check out the Levoit Core 600S. It only costs around $300 and boasts a CADR of 410 CFM.

Most air purifiers are designed for small spaces from 100 to 300 square feet. 

With large spaces, a standard air purifier can find it hard to keep the air clean fast enough so pollutants can still hang around and cause problems.

For large rooms, you need an air purifier with a higher CADR that can provide 4.8 air changes per hour, even for bigger spaces. 

For example, a 600 sq ft room with a standard ceiling size would require at least 384 CFM to provide the recommended 4.8 air changes per hour

Remember you can also combine air purifiers’ CADR scores so, for example, 2 Smart Air Blast minis could still provide up to 4.8 changes for a space of up to 1300 square feet. 

Before we recommend any air purifier, we test air cleaning performance in our home lab using incense stick smoke; then we track how long each air purifier model takes to remove all the PM1 particles from the air.  Combined with long-term costs and our performance data these are the air purifier models we currently recommend for larger rooms.

Don’t rely on the numbers on the box

Some air purifier manufacturers have been known to embellish performance data by overstating the recommended room size for a unit.  Always work out 4.8 air changes for your room space; if you have the square footage of your room, you can use our CADR calculator to work out the CADR you need for that.

Any space over 600 square feet will need either multiple smaller air purifiers or a very large device with bigger filters that last longer but do cost more than what you find for smaller air purifiers. 

In this guide, I will take you through my top recommendations for air purifiers for large rooms based on over 60 devices that we’ve tried and tested at HouseFresh HQ. We’ve put these units through their paces, collected the data and compared them side-by-side.

Staff picks: Top 3 air purifiers for large rooms

I’ve highlighted my top three picks in case you don’t have time to read through my full article:

BEST OVERALLBEST QUIET OPTIONBEST PERFORMANCE TO $ SPENT
Levoit EverestAirSmartAir Blast MiniLevoit Core 600S
AIR CLEANING SPEED ⚡13 minutes17 minutes15 minutes
CADR 👩‍🔬360 CFM (612 m3/h)435 CFM (740 m³/h)410 CFM (697 m³/h)
FILTER TECHNOLOGY 💨3-Stage FiltrationH13 HEPA Filter3-Stage Filtration
MAX ROOM SIZE 📏558 sq. ft.915 sq. ft.635 sq. ft.
WEIGHT ⚖️20.7 lbs (9.38 kg)59 lbs (26.8 kg)13.7 lbs (6.2 kg)
OUR REVIEW 🔍EverestAir reviewBlast Mini reviewCore 600S review
PRICE 💵$499.99$599.00$249.99

Last update on 2024-07-13 / Affiliate links / Images from Amazon Product Advertising API

Those are just the top three options, but there’s more. 

I’ve chosen air purifiers with individual strengths because we all have different needs. Whether it be performance, sound, size or budget, this guide has something for everyone.

1. Best overall: Levoit EverestAir

Incredible performance matched with modern stylings and smart features – the ideal air purifier for large rooms.

Levoit is known worldwide for its high-performing air purifiers at affordable prices. Their vast range covers small rooms with the 200S to mid-sized spaces with the Core 400S to large rooms and for those, my favorite of the bunch is the EverestAir. 

It’s no secret that I’m a fan of Levoit air purifiers, so I was looking forward to receiving this new addition to the Levoit family. Let me explain why.

What we really like

It has adjustable vent angles for optimal airflow
It is compatible with Levoit’s VeSync app to control settings, check filter life and set timers through your phone
It also has voice control through Amazon Alexa and Google Assistant
It’s easy to replace the filters
It offers outstanding air cleaning speed — it cleaned our test room in just 13 minutes

What we think could be better

It is a high-priced unit, especially compared to other Levoit air purifiers
The filters are also expensive, but they last long  — up to 15 months

From the moment I opened the box, the EverestAir didn’t disappoint. The EverestAir’s control panel features touchscreen buttons for a quiet sleep mode, auto mode and a mighty turbo mode. It goes the extra mile by displaying particulate matter readings from the environment’s air quality, thanks to the built-in three-channel sensor that detects PM1.0, PM2.5 and PM10.

This powerhouse of an air purifier is the fastest we have had in our performance testing home lab — it took a mere 13 minutes to clean all of our simulated contaminants from the air.

Adding to its outstanding performance, the EverestAir has smart features such as auto mode, an in-built air quality sensor and app connectivity so that you can monitor the air quality in your large room as well as the ability to change its setting from anywhere in the world (with an internet connection).

Its three-stage filter system includes a washable pre-filter, a high-performance main filter and an activated carbon filter that can effectively remove a wide variety of indoor pollutants. With a high CADR of 360 CFM and a powerful VortextAir fan, the EverestAir is designed can tackle pollutants in large spaces. It’s so powerful that when we tested its particle removal speed at its lowest speed it was still able to clean the in 25 minutes whilst making next to no sound.

That’s why it’s my top recommendation if you have a large room that needs an air quality boost.

HouseFresh rating:★★★★★
Time to clean our 728 cubic feet test room (with the device running at top speed):14 minutes
Air purifier technology:3-Stage Filtration (Pre-filter for large particles, main filter for airborne particles, high-efficiency activated carbon filter for odors and gasses)
Recommended room size (4.8 air changes per hour):563 sq. ft.
Clean air delivery rate (CADR):Dust: 365 CFM
Smoke: 363 CFM
Pollen: 428 CFM
Dimensions (in inches / in cm):18.9L x 8.5W x 23.2H inches (48L x 21.6W x 58.9H cm)
Weight (in pounds / in kg):20.7 lbs (9.39 kg)
Filter life:12-15 months
Noise level in decibels (measured from 3 ft. away with a sound level meter):Speed 1: 39.1 dB
Speed 2: 43.2 dB
Speed 3: 48.6 dB
Turbo: 57.8 dB
Electricity consumption in watts (recorded with an electricity usage monitor):Standby mode: 1.26 watts
Speed 1: 9.85 watts
Speed 2: 15.59 watts
Speed 3: 26.6 watts
Turbo: 69.8 watts
Estimated running cost (electricity consumption + official filter replacement):$206.36 per year
Cost per CADR cfm (based on dust CFM as reported by AHAM):$1.37
Manufacturer’s warranty:2 years
Country of manufacture:China

Read our full review

2. Best performance to $ spent: Levoit Core 600S

A powerhouse of cleaning performance with a budget price tag – can tackle large rooms effectively and with energy efficiency.

I know what you’re thinking. “Why should I consider another Levoit air purifier when you just told me how good the EverestAir is?” Yes, the EverestAir is amazing, but it is also expensive. So, if budget is a big factor, then the Core 600S might be the way to go.  

Inside the 600S is Levoits 3-in-1 pre-filter, signature main filter and Activated Carbon filter. As they come as an all-in-one spherical piece, it is easy to replace, as you can see from our instructional video. Replacements will set you back around $60 for a genuine Levoit filter, but you can get an unofficial replacement for around $45

What we really like

It clears large rooms rapidly — the Core 600S cleared our home lab in just 15 minutes, that’s two minutes slower than the top pick on this list
It doesn’t use much power
It can be connected to the Levoit app
It offers a high CADR for the cost of the unit

What we think could be better

It is not the most eye-catching design
The pre-filter can’t be removed to clean

It may not be the prettiest large air purifier to look at, but when it comes down to cleaning the air in a large room, the 600S won us over with its high CADR of 410 CFM, clearing our performance testing room in just 15 minutes. The Core 600S is ideal if you’re looking for high performance at a low cost.

When it comes to high-performing air purification at a low cost, the 600S is a clear winner and my number two recommendation to clean large rooms of pollutants. This air purifier has everything you’ll need to achieve excellent air quality with smart features like auto mode, numerical and color air quality monitor, app connectivity and a timer. The controls are easy to use and intuitive, making the 600S extremely user-friendly.

HouseFresh rating:★★★★★
Time to clean our 728 cubic feet test room (with the device running at top speed):15 minutes
Air purifier technology:3-Stage Filtration (Pre-filter for large particles, main filter for airborne particles, high-efficiency activated carbon filter for odors and gasses)
Recommended room size (4.8 air changes per hour):584 sq. ft. 
Clean air delivery rate (CADR):Dust: 373 CFM
Smoke: 377 CFM
Pollen: 437 CFM
Dimensions (in inches / in cm):12.3 x 12.3 x 23.6 inches (31.3 x 31.3 x 60 cm)
Weight (in pounds / in kg):13.7 lbs (6.2 kg)
Filter life:6 months
Noise level in decibels (measured from 3 ft. away with a sound level meter):Speed 1: 40.9 dB
Speed 2: 45.9 dB
Speed 3: 61.4 dB
Electricity consumption in watts (recorded with an electricity usage monitor):Standby mode: 1.53 watts
Speed 1: 7.92 watts
Speed 2: 11.35 watts
Speed 3: 21.15 watts
Speed 4: 49.27 watts
Estimated running cost (electricity consumption + official filter replacement):$195.13 per year
Cost per CADR cfm (based on dust CFM as reported by AHAM):$0.80
Manufacturer’s warranty:2 years
Country of manufacture:China

Read our full review

3. The quietest option: Smart Air Blast Mini

This big air purifier with a huge fan and filter, still manages to keep the noise down – even when tackling pollutants in large rooms up to 915 sq. ft.

Smart Air is not your standard air purifier manufacturer. Set up by people who weren’t happy with the cost of air purifiers or their air quality, they set out to make high-performing, low-cost, no-thrills units for the typical household. Smart Air’s answer to cleaning the air in large rooms is the colossal Blast Mini.

Although the name ‘Mini’ confused me slightly (it weighs 59 lbs), there’s no doubt that the Blast Mini is built to last as it is made from metal over the usual plastic body you find on most modern air purifiers.

What we really like

It’s not made from plastic, making it better for the planet
It has a high CADR – perfect for large rooms
It is easy to use, thanks to its one-dial operation
Its HEPA filter lasts much longer than some other filters

What we think could be better

It’s a heavy unit, weighing 59 lbs (26.8 kg)
It doesn’t look as cool as their smaller Smart Air S air purifier

Once we got it up the stairs (it took me and Danny to lift it up to take it to our HouseFresh home lab), this high-efficiency air purifier showed us how well it performs by clearing the air from incense smoke pollutants in our test room in 17 minutes.

When you lift off the front of the unit, you discover its powerful fan and a huge, long-life H13 HEPA filter. Unfortunately, the Blast Mini doesn’t have an Activated Carbon filter as standard. We highly recommend you spend a little extra to have this included in your initial purchase, or you can purchase one separately here.

There are no special bells and whistles on the Blast Mini like auto mode, air quality monitor or touch screen control, but the Smart Air Blast Mini looks great, will last a long time and is highly effective at clearing contaminants from large rooms.

HouseFresh rating:★★★★★
Time to clean our 728 cubic feet test room (with the device running at top speed):12 minutes
Air purifier technology:H13 HEPA filter (and optional activated carbon filter)
Recommended room size (4.8 air changes per hour):703 sq. ft.
Clean air delivery rate (estimated CADR):435 CFM
Dimensions (in inches / in cm):22.6L x 13W x 24.8H inches (57.5L × 33W × 63H cm)
Weight (in pounds / in kg):59 lbs (26.8 kg)
Filter life:13 months
Noise level in decibels (measured from 3 ft. away with a sound level meter):Speed 1: 44.9 dB
Speed 2: 51.2 dB
Speed 3: 56.3 dB
Electricity consumption in watts (recorded with an electricity usage monitor):Standby mode: 0 watts
Speed 1: 51.9 watts
Speed 2: 87.4 watts
Speed 3: 122.7 watts
Estimated running cost (electricity consumption + official filter replacement):$311.89 per year
Cost per CADR cfm (based on dust CFM as reported by AHAM):$1.38
Manufacturer’s warranty:1 year
Country of manufacture:China

Read our full review

4. Best on/off ionizer function: AirDoctor AD3000

It’s not just hype – With a precise auto mode function and UltraHEPA filters, this powerful, large-room air purifier clears pollutants from your air fast.

Since its conception in 2016, AirDoctor has proved itself to be a high-performance air purifier that makes light work of removing pollutants in large rooms at an impressive speed. Designed in the U.S. and manufactured in China, the AD3500 provides all the functionality we expect from a modern air purifier.

The AD3500 may not look like the Belle of the Ball (in my opinion), but what it lacks in style, it makes up in performance and reliability.

What we really like

It was fast at removing pollutants as it cleared our performance testing room in 14 minutes
The auto mode kicked in straight away
Its UltraHEPA filter performed at a high standard in a third-party lab test
The AQI is bright, bold and located on the front of the unit

What we think could be better

There’s no app connectivity, although you can upgrade to the 3500i model at an extra cost
I wish it were more stylish. The white box is a tired design

In our performance tests, the AD3500 stood tall next to our other air purifiers for large rooms like Levoits EverestAir and Core 600S. It even outperformed some of the more popular, more expensive units like the BreatheSmart 75i from Alen and the mighty IQAir Healthpro Plus.

We tested this air purifier both with and without the ionizer being engaged so that we could see how much of a difference it actually made. As you can see from the graphs, the AD3000 cleared our testing room in an impressive 14 minutes (with ionizer function enabled) and 16 minutes (without ionizer function).

Test with ionizer:

Test without ionizer:

Inside the AD3500 is their UltraHEPA filter, separate activated carbon filter and a pre-filter that can be removed and cleaned. AirDoctor claims its UltraHEPA filter is 100 times better than a standard HEPA filter. It’s a bit of a marketing trick to say this, as all filters can trap very tiny particles thanks to Brownian Motion, but we can assume they must use a high-grade HEPA filter, which can trap more particles in a single pass.

As for functionality, there are four fan speeds to choose from, a timer, light dimmer, ionizer and an extremely proficient auto mode. On the front of the unit sits the bright AQI (Air Quality Monitor) circle that clearly indicates your air quality.

HouseFresh rating:★★★★☆
Time to clean our 728 cubic feet test room (with the device running at top speed):14 minutes (with ionizer function enabled)
16 minutes (without ionizer function)
Air purifier technology:UltraHEPA filter and dual-action Carbon/Gas Trap/VOC filter
Recommended room size (4.8 air changes per hour):521 sq. ft.
Clean air delivery rate (CADR):Dust: 339 CFM
Smoke: 336 CFM
Pollen: 356 CFM
Dimensions (in inches / in cm):19.87D x 27.16W x 12.38H inches (50.4D x 69W x 31.4H cm)
Weight (in pounds / in kg):18 lbs (8 kg)
Filter life:UltraHEPA filter: 12 months
Carbon/Gas Trap/VOC filter: 6 months
Noise level in decibels (measured from 3 ft. away with a sound level meter):Speed 1: 40.2 dB
Speed 2: 50.5
Speed 3: 58.2 dB
Speed 4: 63.6 dB
Electricity consumption in watts (recorded with an electricity usage monitor):Standby mode: 0.5 watts
Speed 1: 9.6 watts
Speed 2: 17.6 watts
Speed 3: 39.9 watts
Speed 4: 93.2 watts
Estimated running cost (electricity consumption + official filter replacement):$267.16 per year
Cost per CADR cfm (based on dust CFM as reported by AHAM):$1.53
Manufacturer’s warranty:1 year
Country of manufacture:China

Read our full review

5. Best for VOCs: IQAir Healthpro Plus 

For those serious about removing VOCs from your large room – this Swiss-made air purifier contains over 5 lbs of activated carbon.

The IQAir Healthpro Plus is easily the largest air purifier we have tested. This Swiss-made mammoth of a unit is ideal for those serious about air quality. Our founder, Danny, has the pleasure of running this air purifier in his main hallway (connecting the dining room with the TV room and the living room) every day and insists it is the perfect unit for those with a large open space. 

But that’s not the only reason why I included this air purifier on the list. IQAir has packed the Healthpro Plus’ V5-Cell filter with over 5 lbs of activated carbon and KMn05 alumina, making it the most effective filter for clearing VOCs and odors when compared to every other unit in this guide.

What we really like

Each unit is performance tested in a lab before it’s shipped
There is no ionizer
It comes with a 10-year warranty
It has wheels so you can easily move from room to room

What we think could be better

It is an expensive unit
There is no auto mode

The Healthpro Plus may be large, but it doesn’t waste any of that space. Inside, you’ll find a large, high-performance fan that pushes the air in your room through various filters. IQAir’s PreMax pre-filter traps larger particles, the V5-Cell filter absorbs gas and odors, and the HyperHEPA filter captures harmful microscopic particles from the air.

This behemoth cleared our performance testing room of airborne contaminants (including VOCs) in only 25 minutes with its CADR of 300 CFM, proving it can handle cleaning the air in large rooms with ease.

With a remote control included and a digital display on the control panel, the Healthpro Plus is easy to use. It has five fan speeds to choose from, and you can program a schedule so you don’t need to think about turning it on/off throughout the day.

HouseFresh rating:★★★★★
Time to clean our 728 cubic feet test room (with the device running at top speed):24 minutes
Air purifier technology:HyperHEPA and V50-CELL gas and odor filter
Recommended room size (4.8 air changes per hour):1125 sq. ft. 
Clean air delivery rate (CADR):Dust: 250 CFM (HouseFresh estimate)
Dimensions (in inches / in cm):28H x 18W x 16D inches (71H x 38W x 41D cm)
Weight (in pounds / in kg):35 lbs (15.88 kg)
Filter life:4 years
Noise level (measured from 3 ft. away):Speed 1: 36.9 dB
Speed 2: 37.2 dB
Speed 3: 40.9 dB
Speed 4: 47.2 dB
Speed 5: 53.9 dB
Speed 6: 61.2 dB
Electricity consumption in watts (recorded with an electricity usage monitor):Standby mode: 1 watts
Speed 1: 16.5 watts
Speed 2: 32.7 watts
Speed 3: 47.3 watts
Speed 4: 69 watts
Speed 5: 94.3 watts
Speed 6: 145.2 watts
Estimated running costs (electricity consumption + filter replacements):$421.47 per year
Cost per CADR cfm (based on dust CFM as reported by AHAM):$3.60
Manufacturer’s warranty:10 years
Country of manufacture:Switzerland / Germany

Read our full review

6. The best warranty: Alen BreatheSmart 75i

The ultimate peace of mind with a lifetime warranty – contaminants don’t stand a chance.

When you buy an air purifier (or any product for that matter), you need peace of mind that it’s not going to crap out on you at any given point, and even if it does, you want to know that it can be fixed. If a lengthy warranty is high on your priority, check out units from Alen, as they offer a lifetime guarantee (with product registration and active filter subscription).

Alen’s range of high-performance units suits a variety of budgets and room sizes. My choice for large rooms has to be the BreatheSmart 75i, as it’s capable of cleaning pollutants in spaces up to 1,300 sq. ft., making it a great option for your large living room, open plan kitchen and/or basement. 

What we really like

It cleared our performance testing room in 24 minutes
The pre-filter can be removed and cleaned
Replacing the HEPA filter is quick and easy
It’s pretty quiet even when running on max fan speed

What we think could be better

Weighing 27 lbs, it’s heavy
I wish it was more stylish

What makes the BreatheSmart 75i ideal for large rooms is its powerful fan, thick H13 HEPA filter and Activated Carbon filter that contains pellets of carbon instead of the less effective bonded sheet you find in many units. This powerful mix created the conditions for the BreatheSmart 75i to perform very well in our home lab cleaning tests by clearing our simulated contaminants in just 24 minutes, which is why I’ve chosen it as a great option for use in large rooms.

With the 75i, Alen offers a choice between three filters to suit your air quality needs:

Alen Air Filter B7-Pure Replacement H13 True HEPA FIlter for BreatheSmart 75i Air Purifier - Captures Allergens, Dust, & Mold (1 Filter)
Alen Air Filter B7-Fresh Replacement HEPA Filter for BreatheSmart 75i Air Purifier - Captures Allergens & Mold + Odors & Smoke (1 Filter)
Alen Air Filter B7-Odor Replacement True HEPA Filter for BreatheSmart 75i Air Purifier - Captures Allergens & Mold + Pet Dander & Odors (1 Filter)
Technology
Standard medical-grade H13 True HEPA filter provides outstanding protection for your home’s largest spaces, removing 99.99% of dust, allergens, and harmful fine pollutants as small as 0.1 microns. Enjoy 1,300 SqFt of healthy air every 30 minutes.
Get all the wellness benefits of our standard medical-grade H13 True HEPA filter plus the power of activated carbon for added protection against toxins like volatile organic compounds (VOCs), pollution, and smoke. Capture 99.99% of harmful particles as small as 0.1 microns and keep your home’s air smelling incredibly fresh.
For clean and fresh-smelling air in any pet-friendly home, trust Alen’s patented nontoxic technology to instantly destroys odors at the molecular level. Stop unpleasant smells from accidents, litter boxes, and stinky pets while Alen’s legendary medical-grade H13 True HEPA filtration purifies 1,300 SqFt every 30 minutes.
Price
$99.00
$129.00
$139.00
Filter
Alen Air Filter B7-Pure Replacement H13 True HEPA FIlter for BreatheSmart 75i Air Purifier - Captures Allergens, Dust, & Mold (1 Filter)
Technology
Standard medical-grade H13 True HEPA filter provides outstanding protection for your home’s largest spaces, removing 99.99% of dust, allergens, and harmful fine pollutants as small as 0.1 microns. Enjoy 1,300 SqFt of healthy air every 30 minutes.
More information
Price
$99.00
Filter
Alen Air Filter B7-Fresh Replacement HEPA Filter for BreatheSmart 75i Air Purifier - Captures Allergens & Mold + Odors & Smoke (1 Filter)
Technology
Get all the wellness benefits of our standard medical-grade H13 True HEPA filter plus the power of activated carbon for added protection against toxins like volatile organic compounds (VOCs), pollution, and smoke. Capture 99.99% of harmful particles as small as 0.1 microns and keep your home’s air smelling incredibly fresh.
More information
Price
$129.00
Filter
Alen Air Filter B7-Odor Replacement True HEPA Filter for BreatheSmart 75i Air Purifier - Captures Allergens & Mold + Pet Dander & Odors (1 Filter)
Technology
For clean and fresh-smelling air in any pet-friendly home, trust Alen’s patented nontoxic technology to instantly destroys odors at the molecular level. Stop unpleasant smells from accidents, litter boxes, and stinky pets while Alen’s legendary medical-grade H13 True HEPA filtration purifies 1,300 SqFt every 30 minutes.
More information
Price
$139.00


The 75i we bought may look like a flat white box, but Alen does offer different color front panels to give it a more aesthetic look to match the decor of your room. You can choose from Oak, Weathered Gray, Brushed Stainless, Graphite and Espresso.

HouseFresh rating:★★★★☆
Time to clean our 728 cubic feet test room (with the device running at top speed):24 minutes
Air purifier technology:True HEPA H13 filters with activated carbon pellets + Ionizer technology
Recommended room size (4.8 air changes per hour):512 sq. ft. 
Clean air delivery rate (CADR):Dust: 335.3 CFM
Smoke: 330.5 CFM
Pollen: 403.4 CFM
Dimensions (in inches / in cm):27H x 18.5W x 11.5D inches (68.58H x 46.99W x 29.21D cm)
Weight (in pounds / in kg):27 lbs (12.2 kg)
Filter life:12 – 15 months
Noise level in decibels (as reported by the manufacturerv):24 – 49dB
Electricity consumption in watts (as reported by the manufacturerv):Lowest fan speed: 1.8 watts
Highest fan speed: 45 watts
Estimated running cost (electricity consumption + official filter replacement):$162.12 per year
Cost per CADR cfm (based on dust CFM as reported by AHAM):$2.23
Manufacturer’s warranty:Lifetime (with product registration & active filter subscription)
Country of manufacture:China

Read our full review

7. Best DIY option: Corsi–Rosenthal Box

Get clean air without breaking the bank – Take the DIY approach.

The brainchild of Dr. Richard Corsi and Jim Rosenthal, this do-it-yourself unit uses the basic principle of what an air purifier is…a fan and a filter. There are no fancy functions or features, auto mode or air quality sensors, which can be a con or a pro, depending on your opinion (I like fancy functions and Danny is a purist). 

With a few simple ingredients, you can build a high-performance air purifier for your large room and still have money left over for your vacation fund.

What we really like

Best cleaning performance per dollar spent out of all of units in this list 
Items are easy to come by; you might already have some of them lying around
It is easy to use – simple on/off operation
It’s straightforward to build

What we think could be better

It’s large and pretty ugly
Doesn’t have any additional functions or features

The only way to prove if a Corsi–Rosenthal Box works is to build one and test it…so that’s exactly what we did. We were blown away by the data we collected from our performance tests. The CR Box removed all the contaminants from our room in just 25 minutes.

That’s very impressive when you compare it to the other units in our selection, and it costs a fraction of what big brands charge for their air purifiers. 

If you prefer the simple life, save yourself a chunk of money by making your own Corsi–Rosenthal Box for your large room. Check out our full review by clicking the link below.

HouseFresh rating:★★★★★
Time to clean our 728 cubic feet test room (with the device running at top speed):25 minutes
Air purifier technology:MERV 13
Recommended room size (4.8 air changes per hour):680 sq. ft.
Clean air delivery rate (CADR):Estimated: 274 CFM 
Dimensions (in inches / in cm):20L x 20W x 20H inches (50L x 50W x 50H cm)
Weight (in pounds / in kg):10 lbs (4.5 kg)
Filter life:6-12 months
Noise level in decibels (measured from 3 ft. away with a sound level meter):Speed 1: 49 dB
Speed 2: 55.1 dB 
Speed 3: 60.7 dB
Electricity consumption in watts (recorded with an electricity usage monitor):Standby mode: 0 kWh
Speed 1: 40.5 kWh
Speed 2: 44.5 kWh
Speed 3: 46.7 kWh
Estimated running cost (electricity consumption + official filter replacement):$125.13 per year
Cost per CADR cfm (based on dust CFM as reported by AHAM):$0.29
Manufacturer’s warranty:n/a
Country of manufacture:China

Read our full review

Other units we tested but don’t recommend for large rooms

  • Austin Air HealthMate – A large, robust, American-made air purifier containing a filter packed with 15 lbs of activated carbon for dealing with VOCs. But, it didn’t have the cleaning power in our performance testing that we expected from a unit of this size. It only managed to clear the pollutants in our home lab in 37 minutes

  • Blueair Blue Pure 211+ – This was a strong contender for our guide. It’s powerful, contains effective filters, looks really cool and is extremely easy to use. It didn’t make my list for one reason: you can’t disable its ionizer — and you know how I feel about that particular technology.

  • PuroAir HEPA 14 240 – If you read the intro, you’ll know why this unit is in the ‘don’t recommend’ section: it simply doesn’t clean the air effectively in large spaces despite the manufacturers’ bold claims. It’s a knock-off Levoit Core 300 that doesn’t look or run as well and doesn’t have the Levoit standard.

What to look for when buying an air purifier for a large space

Large rooms can be a blessing and a curse. All that space is great, but it can be a place for vast amounts of pollutants to thrive that can cause health issues for you and your family.

As well as information from the EPA and the WHO (see above), the NIEHS (National Institute of Environmental Health Services) gives us in-depth information about the types of indoor pollutants and the adverse effects on your health they can cause.

Of course, you want the air in your room to be clean and fresh, but with so many devices on offer, which air purifier will best suit your needs and wants? Not all air purifiers are created equal. Some are better than others in cleaning performance, filter technology and features. Some are made for small spaces, some are made for large rooms.

I know how much of a minefield it can be to choose the right air purifier for your large room. That’s why I’ve carefully selected these particular units using a certain set of criteria:

1. Air cleaning performance

This was my top priority when choosing these air purifiers for large rooms. For a unit to be able to remove airborne pollutants in large areas effectively, it must have a powerful fan with a high CADR (Clean Air Delivery Rate).

We timed how long it took for each air purifier to remove contaminants from the air in our home lab so that we could determine how powerful their cleaning performance was. This also allowed us to compare our units to determine which are appropriate for large rooms.

To help you find the right air purifier for your room, we’ve knocked up a CFM calculator where you can enter the dimensions of your room to find what specifications you will require from your air purifier.

2. HEPA filtration

There are different types of filters that manufacturers use in their air purifiers. When we’re looking for units to review, we always sway toward those that contain HEPA filters. From our research, we’ve seen that HEPA filters are the most effective way of removing harmful particles from the air. Using a tightly woven maze of fibers, HEPA filters trap microscopic pollutants from the air passing through them, leaving you with fresh, clean air to breathe.

Dyson has recently (August 2023) made a claim to the National Advertising Division claiming that the use of the word HEPA in Levoit’s branding was misleading, forcing Levoit to remove it from their products.

Through our own performance testing, we’ve found the filters that Levoit uses in their products to be highly effective and will continue to recommend them even if they aren’t technically HEPA.

3. Budget friendliness

When looking for an air purifier that fits your budget, it’s not only the initial price of the unit you need to consider. Air purifiers are electrical devices that need energy to operate. The efficiency of the unit will dictate how much it will cost to run and as it’s recommended to run your air purifier 24/7, this is an important factor.

Another cost to consider is the price of replacement filters. The filters used in these air purifiers need to be replaced periodically in order to keep the unit running efficiently and effectively. Different replacement filters have a wide range of costs and can last anywhere from 6 months to 4 years, so it’s important to factor this into your budget.

4. Control panel and smart features

This part is completely up to you. Think about which features you need, which you want and which you can live without. For example, I use Auto mode most of the time, so I need an air purifier with this feature. I also like monitoring the air quality of my rooms using an app on my smartphone, but ultimately I would choose performance over app connectivity.

Frequently asked questions about air purifiers

The answer is yes…but, it needs to be an air purifier that’s engineered to work in large spaces. Different models of air purifiers are manufactured to operate in different-sized spaces. The manufacturer usually states this data in the specifications of the device, and we add it to our Specs & Features table on each product review.

When it comes to clearing contaminants from a large room, the actual size of the air purifier doesn’t matter. It all depends on how powerful the unit is. We measure this using CADR to determine of efficient a unit is. 

The general rule is the higher the CADR, the more powerful an air purifier is.

The simple answer is no. Introducing a big air purifier into a small room will: 

  1. Take up an unnecessary amount of floor space
  2. Use more energy to power a larger unit
  3. Not be using your air purifier to its full potential
  4. Ultimately be a waste of your money

You can if you like, but it would make a lot more sense to have one right air purifier to suit your room size instead of using two. More than one air purifier in a room will increase the noise, increase the amount of electricity used, and you’ll have to buy replacement filters for each unit.

If you have an HVAC system instem installed, you can buy filters so that it works as a whole house air purifier. The closest thing to a whole house air purifier on this guide would be the powerful IQAir Healthpro Plus, which can be wheeled in and out of rooms as you need. Unless your whole house is one room, I highly recommend finding the right air purifier to suit each room.

The general rule is the higher the CADR, the more powerful an air purifier is.

Wrapping up

With so many large air purifiers on the market, it can be hard to choose which one will suit your air quality needs, look good in your home and won’t cost too much to run each year. When selecting the suitable unit, think about the size of the unit itself, what filters it uses, the CADR, how much it will cost you to run and the price of replacement filters.

Take my word for it; size does matter when it comes to air purifiers.

About HouseFresh

Our team has been writing about air purifiers since the days of the Sharper Image Ionic Breeze, and we have tested and reviewed more than 60 of the best air purifiers on the market in the last three years.

The main way that we evaluate air cleaning performance is by testing how fast each model can remove PM1 pollutants from our home test room of 728 cubic feet. You can read more about our testing process and be sure to check out our air purifier reviews that show the level of detail and data we share with each device we evaluate.

We are an independent publication, refuse to run ads and don’t have any deals with manufacturers behind closed doors. That means we are free to say when an air purifier sucks. 

If you need more help or want to ask us a question, I look forward to your email: daniel@housefresh.com 

Last update on 2024-07-13 / Affiliate links / Images from Amazon Product Advertising API

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About the author

Teddy Booth

Teddy was a senior content producer for HouseFresh between 2019 and 2024 producing written content as well as product photography. He supported Danny as a product tester and lead how-to writer.

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