Best air purifiers – tried and tested for improving indoor air quality

The best air purifiers for improving indoor air quality and filtering dust, pollen and odours, as tested by the Ideal Home team. Our top recommendations from Blueair, AEG, Levoit, Philips, Dyson, and more

The best air purifier as tested by Ideal Home - the Blueair Blue Max 3250i on a blue background
(Image credit: Future)

The best air purifiers can filter out all sorts of airborne contaminants, including smoke, dust, pollen, and pet dander, making it easy to manage your indoor air quality at the press of a button.

Some air purifiers can also tackle invisible airborne particulates such as formaldehyde and Volatile Organic Compounds (VOCs) – chemicals that can be released into our homes by MDF and laminated wood, fire retardants used on upholstery fabrics, paints, and cleaning products amongst other culprits. Plus, they can reduce indoor pollution caused by vehicle emissions entering the home – something of particular relevance if you live in an area where clean air isn't guaranteed when you open the window.

No wonder that, alongside the best dehumidifiers, air purifiers are fast becoming the go-to appliance for those looking to improve their home's air quality.

As such, the Ideal Home team has tried, tested, and reviewed some of the best air purifiers on the market to bring you our top recommendations. We've put air purifiers from Blueair, Dyson, AEG, Philips, and many more through their paces to compare CADR (clean air delivery rate), HEPA filtration performance, ease of use, cost to run, and price, to find the best air purifiers to invest in.

The quick list

Short on time? This quick list is an overview of the very best air filters. You'll find more information on each air purifier and why our testers recommend it if you keep on scrolling.

Best air purifiers

Why you can trust Ideal Home Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.

Best air purifier overall

Blueair Blue Max 3250i Air Purifierproduct badge

(Image credit: Blueair)
A brilliant all-rounder that offers good value for money

Specifications

Recommended room size: 48m²
CADR: pollen 239m³/h, dust 239m³/h, smoke 239m³/h
Filter type: 3-Stage Pre-Filter, HEPASilent Filter with carbon sheet and activated coconut shell carbon
Dimensions: H48 x W27 x D27cm
Weight: 3.39kg
Energy usage: 2.5-20W
Noise levels: 18-46dB
Wi-Fi connectivity: Yes
Automatic mode: Yes

Reasons to buy

+
Excellent performance with fast response times
+
Removal of 99.97% of airborne particles down to 0.1 micron in size
+
Great at odour removal
+
Automatic air quality control
+
Energy efficient
+
Smart App connectivity compatible with Amazon Alexa or Google Assistant
+
Relatively compact and portable

Reasons to avoid

-
On-board controls could be a little easier to use
-
No timer

The Blueair Blue Max 3250i Air Purifier offers a great combination of responsive performance combined with stylish design and a relatively affordable price point, making it our top recommendation for the best air purifier overall. 

It's designed to filter the air in spaces up to 48m² and offers a decent CADR (clean air delivery rate) of 239 m³/h. The 3-Stage HEPASilent Filter also can remove 99.97% of airborne particles down to 0.1 microns in size, whereas many air purifiers at this price point only promise the removal of particulates down to 0.3 microns in size.

In practice, our tests found that the filter made a difference to how the Blueair Blue Max 3250i Air Purifier performed, with this air purifier being one of the fastest to detect dips in air quality and the quickest to improve air quality levels in a small to medium-sized space. It also performed the best at odour removal, clearing the test kitchen of bacon fumes quicker than any other air purifier we tested.

All importantly, the Blueair Blue Max 3250i Air Purifier also offers a built-in air quality sensor that makes managing indoor air quality super simple. Simply turn on the Auto mode and the purifier does all the hard work for you, switching into standby mode when the air quality is good, and automatically kicking into gear should air quality drop. 

The coloured air quality indicator light on the front of the air purifier is a nice user-friendly touch, and, although in testing we thought the on-board controls could be a little slicker, the option to connect to Wi-Fi and operate the air purifier via the Smart App, or to connect it to Amazon Alexa or Google Assistant to use voice-activated commands, will be a great plus point for many users.

Our full Blueair Blue Max 3250i Air Purifier review has more details on our testing process.

Best air purifier for large spaces

AEG AX91-604GY Connected Air Purifierproduct badge

(Image credit: AEG)
Best air purifier for large spaces

Specifications

Recommended room size: 129m²
CADR: 620m3/h
Filter type: 5-Stage Pre-filter, Antibacterial Layer, Pre-charged True EPA12 Filter, Active Carbon, and Ionisation
Dimensions: H72.5 x W31.5 x D31.5cm
Weight: 8.9kg
Energy usage: 4-41W
Noise levels: 17-32dB
Wi-Fi connectivity: Yes
Automatic mode: Yes

Reasons to buy

+
High CADR of 620m3/h that's powerful enough for use in large spaces up to 129m2
+
Automatic air quality control
+
Easy to use
+
Smart App connectivity compatible with Google Home

Reasons to avoid

-
An investment
-
Large and bulky to move
-
Replacement filters are expensive

If you want to manage the indoor air quality within a large room or open-plan home then the AEG AX91-604GY Connected Air Purifier is our top recommendation, with a high CADR of 620m3/h and a cleverly-designed 'AirSurround system' that can spiral the air to all four corners of a 129m² space by way of its powerful fan motor.

All in all, that's nearly three times the CADR of the Blueair Blue Max 3250i Air Purifier, and a similar three-times increase in the size of space that the AX91-604GY can filter. However, the downside is that the AEG AX91-604GY Connected Air Purifier is also nearly three times the price of the Blueair Blue Max 3250i Air Purifier at full RRP, and double the compact 3250i's size and weight.

However, what both of our top recommended air purifiers have in common is stylish design, great functionality and plenty of Smart features that make using them a dream. The AX91-604GY's digital display is especially impressive, winning the accolade for most intuitive and user-friendly design thanks to its six-colour air quality indicator lights and touch-sensitive swipe settings.

The AX91-604GY is also equipped with a hassle-free and energy-efficient automatic mode that uses information gleaned from the built-in air quality sensor to manage your home's air quality. Plus, it's Wi-Fi compatible and can be paired with AEG's Wellbeing App for extra air quality data and functionality, or connected to Google Home. 

It may be an investment – and have the most expensive replacement filters of all the air purifiers we've tested at £100 a pop – but the AEG AX91-604GY Connected Air Purifier does match premium-feel build quality to that premium price tag, and, if you have a large space to filter, then this is an air purifier that's up to the challenge.

Dive into the detail in our AEG AX91-604GY Connected Air Purifier review.

Best budget buy

Blueair Blue Pure 511 Air PurifierBudget buy badge

(Image credit: Blueair)

3. Blueair Blue Pure 511 Air Purifier

A basic air purifier that offers affordability

Specifications

Recommended room size: 38m²
CADR: 191m³/h
Filter type: 3-Stage Pre-Filter, HEPASilent Filter with carbon sheet and activated coconut shell carbon
Dimensions: H34 x W20 x D20cm
Weight: 1.9g
Energy usage: 2-16W
Noise levels: 24-49dB
Wi-Fi connectivity: No
Automatic mode: No

Reasons to buy

+
Affordable
+
Energy efficient
+
Compact and portable

Reasons to avoid

-
No Automatic mode
-
No Wi-Fi connectivity
-
No air quality data
-
No timer

We've now tested multiple Blueair air purifiers and all have scored highly in our review process. The Blue Pure 511 is the brand's entry-level model, specifically designed to make investing in an air purifier more affordable thanks to its budget-friendly sub-£100 price tag. 

The Blue Pure 511 feels a lot more basic in terms of style and functionality than our top-rated Blueair air purifier, the Blue Max 3250i, and it's less powerful, with a 191m³/h CADR that can improve air quality in a space up to 38m² compared to the Blue Max 3250i's 239m³/h CADR that can manage air quality in a space of up to 48m2. But that CADR is still impressive for an air purifier at this price point. In comparison, the cheapest air purifier we've tested (which isn't that much cheaper), the Beko ATP5100I Air Purifier, can only manage air quality in a 13m² space.

A downside for some will be the Blue Pure 511's lack of Wi-Fi connectivity. This means no remote or voice-activated controls and very limited air quality data. However, the biggest downside, in our opinion, is the fact the Blue Pure 511 doesn't offer a built-in air quality sensor. This means the Pure 511 is either on or off, with no Automatic mode whereby it will manage its own performance according to the air quality it detects. You can toggle the Pure 511 through three fan speeds for low, medium, or high filtration, but without Automatic mode, that still makes for very limited functionality. And unlike models with built-in air quality sensors, that means there's no air quality data available with the Pure 511. Personally, if possible, we would spend more and opt for the Blue Max 3250i instead. 

However, if price is paramount, this air purifier still does a decent job in a small space. And although it lacks that energy-efficient Automatic mode, the Blue Pure 511 does deliver relatively low energy usage, using just 2-16W of electricity.

Best air purifier for small spaces

Levoit Core 300S Air Purifierproduct badge

(Image credit: Levoit)
A compact air purifier that's useful for small rooms

Specifications

Recommended room size: 50m²
CADR: 240m3/h
Filter type: 3-Stage Pre-Filter, H13 HEPA Filter, Activated Carbon Filter
Dimensions: H36 x W22 x D22cm
Weight: 2.7kg
Energy usage: 23W
Noise levels: 22-50dB
Wi-Fi connectivity: Yes
Automatic mode: Yes

Reasons to buy

+
Compact and portable
+
Automatic air quality control
+
Easy to use with great display
+
Smart App connectivity compatible with Amazon Alexa or Google Assistant

Reasons to avoid

-
Not as responsive as some

If you have small rooms, and you're looking for an air purifier that won't take up too much space, then the Levoit Core 300S air purifier is a good choice.

Its H36 x W22 x D22cm build isn't that much smaller than the H48 x W27 x D27cm Blueair Blue Max 3250i Air Purifier at the top of our list, but its shorter stature does make a difference, allowing the Core 300S to fit much more easily onto a sideboard or work surface if you don't have the floor space to accommodate a larger design.

It also offers a great user experience, with an easy-to-read display panel that instantly communicates your room air quality levels via coloured indicator lights and super easy-to-use onboard controls. This air purifier is also Wi-Fi compatible so you can pair it with the VeSync Smart App to operate it remotely and view more detailed real-time data on your home's air quality, or connect it to Amazon Alexa or Google Assistant if you prefer to operate your appliances via voice commands. 

In our tests, it also did a good job of air filtration thanks to its 3-stage pre-filter, H13 HEPA filter, and activated carbon filter. 

Like the Blueair Blue Max 3250i Air Purifier, the Levoit Core 300S includes that all-important built-in air quality sensor and automatic mode so you can leave it on standby to manage your air quality automatically. However, it wasn't quite as quick at responding to dips in air quality as the Blueair Blue Max 3250i Air Purifier, perhaps because the Levoit Core 300S air purifier promises to capture 99.97% of 0.3-micron air pollutants, whereas the Blue Max 3250i filters out microns down to 0.1 in size. As such it didn't do quite as good a job at odour removal as the Blue Max 3250i.

That said, if you're looking for a small air purifier – that you can perhaps pop on a kitchen work surface or bedside table – this compact design fits the bill and offers a super user-friendly design.

Our Levoit Core 300S Air Purifier review has all of the details.

Best for air quality data

The Philips AC3033/30 Expert Series 3000i Connected Air Purifier a grey cylinder designproduct badge

(Image credit: Philips)
A powerful air purifier with excellent air quality data

Specifications

Recommended room size: 135m²
CADR: 520m³/h
Filter type: HEPA filter and activated carbon filter
Dimensions: H64.5 x W29 x D29cm
Weight: 6.8kg
Energy usage: 2-55W
Noise levels: 15-56dB
Wi-Fi connectivity: Yes
Automatic mode: Yes

Reasons to buy

+
High CADR of 520m3/h that's powerful enough for use in large spaces up to 135m2
+
Excellent air quality data at your fingertips
+
HEPA air filter with activated carbon
+
Auto mode
+
Quiet Sleep mode
+
Easy to use
+
Wi-Fi connectivity

Reasons to avoid

-
An investment
-
Large and bulky to move
-
Replacement filters are expensive

A powerful air purifier that's designed to manage air quality in larger spaces, the Philips 3000i Series offers a 520m3/hr CADR that promises to remove impurities in areas up to 135m². 

In all of our air quality tests, the 3000i Series responded fast and effectively, identifying and filtering out a variety of airborne particulates in record time. Its performance was on par with our two top-rated air purifiers, the Blueair Blue Max 3250i (which remains the more affordable choice for small to mid-sized rooms) and AEG AX91-604GY Connected air purifier (which just pips the 3000i Series to the post for larger spaces by offering a higher 620m3/h CADR).

Our reviewer found the 3000i Series LCD control panel extremely user friendly, and a built-in air quality sensor means you can switch this air purifier into Automatic mode for hassle-free operation. 

That sensor also means the 3000i Series offers some of the best air quality data of any air purifier we've tested. Unlike most premium air purifiers, the 3000i Series doesn't just use coloured lights to communicate basic air quality levels, you can also access in-depth real-time readings of your home's Indoor Allergen Index, PM2.5 levels and gas levels (which measures VOC and odours) on the air purifier's on-board display, as well as utilising the 3000i Series' Wi-Fi connectivity for more information via the Philips Clean Home+ App. Only the Dyson Purifier Hot+Cool Formaldehyde HP09 Fan Heater is on a par in terms of the level of air quality data at your fingertips, but it's a less powerful air purifier, and much more expensive.

Overall, if you want to manage the air quality in a large space we think you'll be very happy with either the Philips 3000i Series or the AEG AX91-604GY, so which to opt for largely comes down to which is available for the better price when you come to shop.

Our full Philips 3000i Series AC3033/30 Connected Air Purifier review has more detail.

Best for multifunctional climate control

Dyson Purifier Hot+Cool Formaldehyde HP09 purifying fan heaterproduct badge

(Image credit: Dyson)
A multifunctional design that offers 3-in-1 climate control

Specifications

Recommended room size: 27m²
CADR: not supplied
Filter type: HEPA H13, formaldehyde catalytic filter, and activated carbon filter
Dimensions: H76 x W22 x D22cm
Weight: 5.5 kg
Energy usage: 6-40 W
Noise levels: 46-62dB
Wi-Fi connectivity: Yes
Automatic mode: Yes

Reasons to buy

+
3-in-1 air purifier, fan, and heater
+
Removal of 99.95% of airborne particles down to 0.1 micron in size, including formaldehyde
+
In-depth air quality data
+
Automatic air quality control
+
Smart App connectivity compatible with Amazon Alexa or Google Assistant

Reasons to avoid

-
An investment
-
Slower to filter the air than many models we tested

If you're looking to control your indoor climate in more ways than one, then Dyson's Hot+Cool Formaldehyde offers a 3-in-1 design that will keep you cool in the summer by way of its powerful oscillating fan, warm you up by expelling hot air in the winter, and purify your home's air to boot.

The Hot+Cool features a HEPA H13 filter that – similarly to the Blueair Blue Max 3250i Air Purifier – claims to capture 99.95% of particles as small as 0.1 microns. However, as the name may suggest, the Hot+Cool also promises to tackle formaldehyde – a potentially harmful chemical that can be found in building materials and household products that Dyson states has molecules 500 times smaller than 0.1 microns – a claim few other air purifiers make. It also features automatic air quality control, and Smart App connectivity that's compatible with Amazon Alexa or Google Assistant.

It's a lot of functionality wrapped up in an uber-stylish design, but the downside is that – although this isn't Dyson's most expensive air purifier – it comes with a price tag that certainly makes our eyes water. Plus, despite that high price tag, the Hot+Cool can only filter the air in a space up to 27m² – that's a lot smaller in area than most of the air purifiers in our round-up. And, although Dyson doesn't provide a CADR rating for its air purifiers, in our tests we found the Hot+Cool slower to clean the air than the air purifiers we've placed higher in our round-up – sometimes considerably slower.

However, this is one of the few air purifiers to offer such a wide scope of multifunctional climate control, and, if you take your air quality seriously, the Hot+Cool Formaldehyde gives you access to the most in-depth air quality data we've come across from an air purifier – both accessible via the on-board controls and the Smart App.

Find more detail in our Dyson Purifier Hot+Cool Formaldehyde HP09 Fan Heater review

Air purifier plus dehumidifier

MeacoDry Arete One 20L Dehumidifierproduct badge

(Image credit: Meaco)
Best air purifier and dehumidifier in one

Specifications

Recommended room size: 42m² / 50m² / 75m² / 90m²
CADR: not provided
Filter type: H13 HEPA filter
Dimensions: H47 x W32 x D24cm / H62 x W37x D27cm
Weight: 10.7kg / 10.9kg / 15kg / 16kg
Energy usage: 151W / 151W / 216W / 267W
Noise levels: 35-38dB / 38-40dB / 40-42dB
Wi-Fi connectivity: No
Automatic mode: No

Reasons to buy

+
2-in-1 air purifier and best-in-class dehumidifier

Reasons to avoid

-
Limited functionality in 'air purification' mode
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No Automatic mode
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No Wi-Fi connectivity
-
No timer

If your home is prone to excess moisture and damp issues like mould and mildew, then, although many air purifiers can help to remove fungal spores from the air, a dehumidifier is going to be the best option for sucking excess moisture from the air in a poorly ventilated indoor space and preventing moisture-related problems from forming in the first place. 

Thankfully you don't have to buy two separate products, with the MeacoDry Arete One Dehumidifier and Air Purifier offering the best of both worlds. This multifunctional unit gets our vote for the best dehumidifier money can buy thanks to its high moisture extraction rate, generous water tank, quiet operation, easy-to-use design, and energy-efficient performance. Its Smart Laundry Mode also makes quick work of drying wet washing. 

You can choose from four size options, that extract 10, 12, 20 or 25 litres of moisture from the air per day respectively, and all offer H13 HEPA filters to improve indoor air quality in more ways than one.

That said, because the Arete One is a dehumidifier first and foremost, you won't get the nuanced air purification you can expect from a standalone air purifier. There's no built-in air quality sensor or automatic mode, so although you can use the air purifier independently of the dehumidify function, it is either switched on or off. And there's no Wi-Fi connectivity or Smart App to view more detailed air quality data.

However, if you're looking to solve damp and air quality issues in one fell swoop, the Arete One offers great versatility and a lot of bang for your buck.

Our MeacoDry Arete One Dehumidifier & Air Purifier review has more detail.

Air purifier plus humidifier

The DH Lifelabs Aaira Mini air purifier with a see through blue perspex body with white feetproduct badge

(Image credit: DH Lifelabs)
A cold evaporation air purifier that also humidifies

Specifications

Recommended room size: 30m²
CADR: not provided
Filter type: Cold Evaporation Filter (CEF) and Cold Evaporation Filter Lid (CEF Lid)
Dimensions: H30 x W22 x D22cm
Weight: 2.4kg (without water)
Energy usage: 21W
Noise levels: <43dB
Wi-Fi connectivity: No
Automatic mode: No

Reasons to buy

+
2-in-1 air purifier and humidifier
+
Compact and portable

Reasons to avoid

-
Low CADR
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Can only filter spaces up to 30m2
-
No Automatic mode
-
No Wi-Fi connectivity
-
No timer

Do you have the opposite problem and want to add moisture to your air? DH Lifelabs Aaira Mini Air Purifier can help. This compact air purifier uses a cold evaporation filter and hypochlorous acid (HOCl) – which the brand states is 'a naturally occurring molecule created using non-iodized salt, water, and electrolysis' – to clean, deodorise, and humidify dry air.

On delivery, the DH Lifelabs Aaira Mini air purifier needs the water tank filling and salt adding, but it's then ready to roll, and our reviewers found it very easy to use. There's no Wi-Fi connectivity, built-in air quality sensor, air quality data, or automatic mode with this mode, just a choice of three fan settings and a disinfectant icon that will flash intermittently when HOCI is being dispersed. 

We weren't wholly sold on the air filter's looks at first – we found it slightly reminiscent of a goldfish tank on first appearance! – especially as the unit's water tank lights up when running on the medium and high fan speeds. However, the light turns off at the lowest fan speed, so you can use this setting overnight if you don't want to be disturbed.

And, our reviewer was particularly impressed by the purifier's impact on air humidity which he found helped to ease his respiratory problems. He says, 'This air purifier definitely made a material difference in stopping my coughing fits and sinusitis. The air felt less congested and the HOCI that is dispersed gave the room an oceanic-like odour'.

Find more details in our DH Lifelabs Aaira Mini air purifier review.

Most affordable air purifier

Beko ATP5100I Air Purifier

(Image credit: Beko)
An entry-level air purifier with all the basic functionality

Specifications

Recommended room size: 13m²
CADR: 110m3/h
Filter type: 3-Stage Pre-Filter, HEPA 13 Filter, Carbon Filter and optional Ionisation
Dimensions: H38 x W20 x D20cm
Weight: 2.3kg
Energy usage: 10W
Noise levels: not provided
Wi-Fi connectivity: No
Automatic mode: No

Reasons to buy

+
Affordable
+
Compact and portable

Reasons to avoid

-
Low CADR
-
Can only filter spaces up to 13m2
-
No Automatic mode
-
No Wi-Fi connectivity

Air purifiers aren't cheap, with very few models available for under £100. However, the Beko ATP5100I Air Purifier can often be found on sale for sub-£100, so if you're looking for an affordable air purifier, it's a model worth considering.

That said, the Beko ATP5100I's low price point does mean a sacrifice in performance. Whilst this air purifier is fitted with a 3-Stage Pre-Filter, HEPA 13 Filter, and Carbon Filter (along with an optional ionisation function) it has a CADR of just 110m3/h, which is one of the lowest of all the air purifiers we've tested, and means the ATP5100I can only filter the air in a space up to 13m².

If you only have a small area that you want to improve air quality in, that may not be a problem. However, what may impact usability more is the ATP5100I's lack of an air quality sensor or automatic mode. What that means in practice is that, unlike most of the other air purifiers in this round-up, you don't get any feedback on your current indoor air quality via the Beko ATP5100I Air Purifier and instead you have to rely on your nose – or possibly itching eyes if you have allergies – to know when to turn the air purifier on and off.

This made a huge difference to usability during our testing process and can make for increased running costs as you may be more inclined to leave the ATP5100I running constantly. And, whilst its 10W energy usage is low, the lack of standby mode could mean your electricity use racks up.

However, if you can live without all of these features – and the lack of Wi-Fi connectivity – it's hard to beat the Beko ATP5100I Air Purifier's price when it's on sale. Plus, replacement air filters are the cheapest of all the air purifiers we've tested, so it's a budget buy in more ways than one.

See how it performed in our Beko ATP5100I Air Purifier review.

How to choose the best air purifier

It would be nice to think that we could all rely on good air quality as a standard, however, with increasing levels of pollution both inside and out, many of us are turning to air purifiers to help counteract potentially harmful particulates in the air.

As biochemist and medical herbalist Dr Chris Etheridge says, ‘There’s mounting evidence that indoor pollution can pose more of a health threat than outdoor pollutants. Improving indoor air quality can be key to tackling conditions like asthma and chronic obstructive pulmonary disease (COPD).’

But what should you be looking for when you shop for the best air purifier? We've broken down the essentials to help you invest in the right air purifier for you.

A selection of five air purifiers of various sizes on a wooden table in a room with pale green walls and indoor plants on shelves

(Image credit: Future / Amy Lockwood)

Clean Air Delivery Rate (CADR)

If you're in the market for an air purifier, then you need to know about CADR. This is shorthand for Clean Air Delivery Rate and measures the volume of air the air purifier can filter, or clean, in a given timeframe. That measurement is usually given per hour, in which case it's measured as m3/h.

As Lars Dunberger, Technology Development Manager at Blueair, a Swedish manufacturer that specialises in air quality products, explains, 'CADR is an industry-standard measure defined by the independent Association of Home Appliance Manufacturers (AHAM) in the U.S. Certified and verified by an independent laboratory, CADR provides consumers with a reliable way to compare the efficiency of different air purifiers. The AHAM recommends a CADR rating of at least 2/3 of the room's area'.

In practice, that means that the higher the CADR rating of an air purifier, the faster it will be able to clean the air, and the larger space it will be able to purify. An air purifier with a low CADR rating may not be as effective in removing pollutants from the air.

Of course, air purifiers with higher CADR ratings tend to come with a higher price tag to match, so its a balancing act of finding a model with a decent CADR that's within your budget. However, if you have very large rooms or an open-plan home then opting for an air purifier with a low CADR to save money will likely be a false economy as it will struggle to do an effective job.

For comparison, the lowest CADR rating in our round-up is the budget Beko ATP5100I Air Purifier with a 110m3/h CADR, and the highest belongs to the powerful AEG AX91-604GY Connected Air Purifier with a 620m3/h CADR.

A white Bosch air purifier in a children's bedroom by the side of bed with striped bedding

(Image credit: Bosch)

Recommended room size

That brings us on to room size. Pretty much all air purifiers come with a manufacturer recommendation for the maximum room size they are suitable for, which is usually measured in m2.

You can work out the m2 of your home's floor space by measuring the width and length of the room, and then multiplying the two numbers. So if your room measures 3 metres in width and 4 metres in length, the square metre measurement would be 12m2 (3 x 4 = 12m2).

As mentioned, it's important to buy an air purifier that matches the size of space you want to filter, otherwise it will struggle to adequately purify the air. 

And, if your home is on two levels, and you don't want to continually carry the air purifier up and down stairs, that may mean investing in more than one air purifier. Our guide to 'how many air purifiers do I need' has more advice for choosing the right number of appliances to effectively manage your indoor climate. 

A cylindrical air purifer by a desk in a home office

(Image credit: Blueair)

HEPA filter

Next, you may want to consider the type of air filter you want your air purifier to be equipped with. 

A HEPA Filter (shorthand for high-efficiency particulate air filter) is the common standard in air purifiers. The United States Environmental Protection Agency defines a HEPA air filter as 'a type of air filter that can theoretically remove at least 99.97% of dust, pollen, mould, bacteria, and any airborne particles with a size of 0.3 microns (µm)' from the air. This is the filter that can help the most if you suffer from things like pet allergies or hay fever.

Most air purifiers that have a HEPA air filter also offer a Pre-Filter of some kind. A pre-filter is designed to capture larger particulates to prevent them from reaching the HEPA filter. If you think of air filtration as sifting sand on a beach then you want to remove the large pebbles first with a big sieve before using a finer one. Otherwise, the fine filter gets clogged up. A pre-filter can help to prevent larger particles from reaching the HEPA filter, and thereby prolong its lifespan.

If you also want your air purifier to filter out odours from the air, most manufacturers will recommend opting for an air purifier with an additional Active Carbon Filter. An active carbon filter is generally thought to filter microscopic particles from the air, like traffic fumes, cigarette smoke, and Volatile Organic Compounds (VOCs) that carry unpleasant smells. They can even remove viruses from the air.

Some air purifiers also offer Ionisation functionality. As air purifier manufacturer AEG states, ionisation produces 'negatively or positively charged particles (negative or positive ions) using electricity. If this functionality is turned on, the air purifier pushes out these negatively charged ions into the room, which then attach themselves to oppositely charged particles in the air - such as dust, bacteria, viruses, pollen, smoke, or other allergens - making them bigger, heavier particles that either attach themselves to surfaces including the ground or are captured by the filters of the air purifier on the subsequent run(s), thereby eliminating them from airborne circulation'.

When you're investing in an air purifier it's important to remember that you will also have the ongoing cost of replacing the main HEPA air filter periodically. How often the filter needs changing will depend on several factors like usage and environment, but manufacturers generally recommend filters are replaced every 6-12 months. 

It's worth researching the cost of replacement filters for the particular air purifier that you're considering investing in before you shop, as they can range from £20 to an eye-watering £100.

The Blueair, Levoit, and Beko air purifier's air filters on a wooden table with indoor plants behind

(Image credit: Future / Amy Lockwood)

Energy efficiency

Thanks to rising energy prices we're probably all concerned about the running costs of an air purifier. 

You can find out more detail in our guide to how much an air purifier costs to run, but to make sure you're not spending more than you need to on running costs the two main factors to consider are the air purifier's wattage and whether it comes equipped with an automatic mode.

The lower the wattage, the less energy the air purifier will use to run. For instance, our #1 recommendation, the Blueair Blue Max 3250i Air Purifier, uses 2.5-20W depending on which mode you have it operating in, whereas the larger and more powerful AEG AX91-604GY Connected Air Purifier requires 4-41W.

However, the biggest factor in better energy efficiency is opting for a model with a built-in air quality sensor and an automatic mode. This means that the air purifier doesn't need to be left running on a high (energy-hungry) fan setting to do its thing, instead, the air purifier will automatically manage its performance in relation to the air quality levels it detects, switching to standby mode when air quality is good and jumping into gear only if air quality dips out of the 'very good' range.

Beko ATP5100I Air Purifier on wooden shelving in a laundry room

(Image credit: Beko)

Noise levels

Lastly, you might want to consider noise levels. As Lars Dunberger, Technology Development Manager at Blueair explains, 'noise from air purifiers generally comes from the fan or motor and the air pressure through the filter'.

Noise levels can differ according to the design of the machine, but most products come with a noise rating to help you know what to expect. This is measured in dB (decibel level) and tends to range between 18-60dB. 

However, as Lars states, 'it should be mentioned that the dB value alone does not provide enough information to determine how “noisy” an air purifier is. The characteristics of noise, tone and how the individual subjectively perceives the noise also weigh in'. This was certainly something we found whilst testing, with some air purifiers with higher dB ratings sounding like easy-to-ignore gushing air in practice, and some appliances with lower dB ratings causing more irritation due to whirring or mechanical noises. 

Most air purifiers offer at least three different fan speed settings, with the low fan speed being the quietest and the high fan speed the noisiest, and many offer a quieter night-time mode. Others are equipped with an automatic mode that means the air purifier remains quiet unless pollution levels rise and it needs to filter the air more aggressively, this means you don't need to leave the appliance running continuously.

An air purifier with legs by the side of a bed in a beige coloured bedroom

(Image credit: Blueair)

FAQs

Do air purifiers really work?

Are air purifiers worth it, do they work, and can I just open the window instead, you might be wondering. 

Well, yes, regular ventilation like opening the windows and doors in your home is key to a healthy building. In fact, this is how long to keep windows open to stop mould, as recommended by the experts. However, if you live in an area with poor outdoor air quality, high road traffic pollution, or are sensitive to pollen, then this isn’t always as good of a solution as we might hope. 

An air purifier works by using a fan to draw air into the air purifying unit whereby it passes through a series of filters that remove particulate matter. The cleaned air is then discharged back into the room. As such, a decent air purifier can be a good way to improve indoor air quality and is worth the investment for those with allergies or sensitivity to airborne pollutants.

Do air purifiers help with dust?

Yes, dust makes up some of the largest particles likely to be in your home's air, so most air purifiers will manage to capture and filter out a good amount of dust particulate from the air. 

Do air purifiers remove smells?

Yes, a good air purifier can remove smells and odours from your home. The best air purifiers for removing smells are those with Activated Carbon Filters alongside the usual HEPA filter. The Activated Carbon can help to remove Volatile Organic Compounds (VOCs) and their accompanying smells – such as the particulates from a scented candle, cleaning products or aerosol deodorants – as well as things like fumes and odours from cooking fumes and pets.

The Blueair Blue Max 3250i Air Purifier is our top recommendation for the best air purifier for removing smells, making short work of removing fried plant-bacon fumes from our test kitchen.

How we test air purifiers

You'll find full details of the Ideal Home review process on our how we test page.

Our team of reviewers tested a host of the best air purifiers on the market to compile this guide. We compared each air purifier's assembly and set-up process, its design, ease of use, CADR (Clean Air Delivery Rate), HEPA air filter performance, energy consumption, and noise levels to compile our top recommendations.

Each air purifier was put through its paces in a real-life home environment to test how well it filtered out cooking fumes when frying bacon, how quickly it removed smoke and VOCs from the air, and how well it combatted dust.

Five air purifiers of various sizes lined up on a tiled floor in a room with a pale yellow wall

(Image credit: Future / Amy Lockwood)

If there are any products included in this guide that we haven't managed to test in person, or the product didn't achieve at least 4 out of 5 stars, then they won't have an Ideal Home Approved badge. However, you can rest assured we've done thorough research on their technical specifications and read multiple happy – and not-so-happy – customer reviews to narrow down our suggestions to only the best-in-class.

Amy Lockwood
Content Editor

After studying Print Design at Winchester School of Art, Amy spent multiple years working in the interior industry as a copywriter, content creator, and product stylist. She’s now Content Editor at Ideal Home, offering expert advice on the best products for decorating your home and ensuring it functions smoothly. That includes sourcing stylish yet affordable furniture – from the best sofa beds for combining style, comfort, and function, to the best artificial Christmas trees for a stress-free festive season – helping our readers to find the best mattress for their sleep style, and testing top-rated dehumidifiers and air purifiers to narrow down the best-in-class.