The short version
- Of the 25 Amazon UK bestseller listings where the maths can be done, 22 advertise a room size that assumes two air changes an hour or fewer. AHAM’s room-size rule assumes 4.8.
- At 4.8 changes an hour, the bestselling Levoit Core Mini’s 34 m² becomes 7.1 m².
- Priced per square metre at that rate, the £159 Winix 5500-2 is the cheapest of our eight picks at £4.70 and the £49.99 Levoit the dearest at £7.06.
- 13 of the 50 bestsellers in the chart on 10 September 2026 are not filter purifiers, including two ozone generators.
An air purifier listing will tell you the size of room it covers. It will rarely tell you how often it cleans the air in that room, and that rate decides the number. We read all 50 listings in Amazon UK’s air purifier bestseller chart on 10 September 2026 and reworked every advertised room size we could at the rate AHAM’s certification scheme uses. The eight picks below run from £49.99 to £260 and are listed by the room they suit at that rate, smallest first.
The short answer
For a bedroom, the Philips 600 Series: £99.99 and a CADR of 170 m³/h, enough for a 14.8 m² room at 4.8 air changes an hour. For a living room, the Winix 5500-2 at £159 covers 33.9 m² at that rate. Size from the CADR: most advertised room sizes assume one or two changes an hour.
Prices and specs last checked 10 September 2026 · next check 1 October 2026 · how we picked
How they compare
All eight picks side by side, smallest room first. CADR, room size and filter details are each seller’s own. The room at 4.8 air changes an hour and the price per square metre are our arithmetic.
| Model | CADR on the listing | Room size advertised | Air changes an hour behind it | Room at 4.8 changes an hour | Price | Price per m² at 4.8 | Genuine filter | Filters over three years |
|---|---|---|---|---|---|---|---|---|
| Levoit Core Mini | Not published | 34 m² | 1 (stated) | 7.1 m² | £49.99 | £7.06 | £21.99, no interval stated | Cannot be worked out |
| Coway Airmega 50 | 120 m³/h | 25 m² | 2 (stated) | 10.4 m² | £59.97 | £5.76 | None found on Amazon UK | Cannot be worked out |
| Philips 600 Series | 170 m³/h | 44 m² | 1.6 | 14.8 m² | £99.99 | £6.78 | £24.99, up to 12 months | £49.98 |
| Blueair Blue Pure 511 | Not published | 38 m² | 2 (stated) | 16 m² (stated) | £84.00 | £5.25 | £25.00, every 6 months | £125.00 |
| DREO HAP008S | 196 m³/h | 79.52 m² | 1.0 | 17.0 m² | £84.99 | £5.00 | £24.99, no interval stated | Cannot be worked out |
| Philips 900 Series | 250 m³/h | 65 m² | 1.6 | 21.7 m² | £139.99 | £6.45 | £39.99, up to 1 year | £79.98 |
| Winix 5500-2 | 390 m³/h | 99 m² | 1.6 | 33.9 m² | £159.00 | £4.70 | £53.37, every 12 months | £106.74 |
| Philips 3200 Series | 520 m³/h | 135 m² | 1.6 | 45.1 m² | £260.00 | £5.76 | £69.99, up to 1 year | £139.98 |
The once-an-hour room
The figure that settles a room size is the clean air delivery rate, or CADR: how many cubic metres of cleaned air a purifier puts out in an hour. Divide it by the room’s volume and you get air changes per hour. AHAM, the US appliance association whose Verifide scheme certifies CADR, bases the room size on its seal on 4.8 changes an hour with an 8-foot ceiling.
We read all 50 listings in Amazon UK’s Air Purifiers bestseller chart on 10 September 2026: title, bullet points, product details and the brand content lower down each page. For 25 of them the air-change rate behind the advertised room size can be worked out, either because the listing states it or because it prints both a CADR and the room size. 22 of those 25 assume two changes an hour or fewer, and 11 assume about one.
| Listing | Room size advertised | How the rate is known | Air changes an hour |
|---|---|---|---|
| Levoit Core Mini | 34 m² | Stated: once an hour | 1 |
| OUNEDA HY1800 Pro | 1,095 ft² (102 m²) | Its own 5 an hour in 215 ft² | About 1 |
| Philips 600 Series | 44 m² | CADR 170 m³/h | 1.6 |
| MELEDEN bedroom purifier | 215 ft² (20 m²) | Stated: 5 times an hour | 5 |
| Winix 5500-2 | 99 m² | CADR 390 m³/h | 1.6 |
| Blueair Blue Pure 511 | 38 m² | Stated: every 30 minutes | 2 |
| GoveeLife Smart (large rooms) | 97 m² | CADR 135 CFM | 1.0 |
| GoveeLife Smart Mini | 376 ft² (35 m²) | Stated: once an hour | 1 |
| AIRTOK AP0601 | 35 m² | Stated: twice an hour | 2 |
| Philips 900 Series | 65 m² | CADR 250 m³/h | 1.6 |
| Blueair Blue Max 3250i | 48 m² | Stated: every 30 minutes | 2 |
| Russell Hobbs (100 m³/h) | 12 m² | CADR 100 m³/h | 3.5 |
| DREO HAP008S | 79.52 m² | CADR 196 m³/h | 1.0 |
| Philips 3200 Series | 135 m² | CADR 520 m³/h | 1.6 |
| Spear & Jackson | 30 m² | Stated: in an hour | 1 |
| Blueair Blue 511i Max | 43 m² | Stated: every 30 minutes | 2 |
| Coway Airmega 50 | 25 m² | Stated: every 30 minutes, 2.4 m ceiling | 2 |
| DREO (269 m³/h) | 109 m² | Stated: once an hour | 1 |
| Chuboor PJ01 | 1,200 ft² (111 m²) | Stated: 1.5 times an hour | 1.5 |
| AIRTOK (large rooms, 280 m³/h) | 170 m² | Stated: once an hour | 1 |
| Blueair Blue Pure Mini Max | 8.6 m² | Stated: every 30 minutes | 2 |
| TENKER (200 m³/h) | 2,180 ft² (203 m²) | CADR 200 m³/h | 0.4 |
| MOOKA (2,200 ft²) | 2,200 ft² (204 m²) | Stated: per hour | 1 |
| OUNEDA ZY3866G | 2,300 ft² (214 m²) | Stated: up to 3 times an hour | 3 |
| AIUZLK KJ80 | 690 ft² (64 m²) | Stated: once an hour | 1 |
How this guide was made: desk research, not a hands-on test. We have no particle counter and have measured nothing. Every CADR, room size, wattage and filter interval below is the seller’s own, read on Amazon UK on 10 September 2026, with genuine replacement filters priced on their own listings the same day. The room size at 4.8 air changes an hour is our arithmetic, assuming a 2.4 m ceiling, and the working is under each table.
Call it the once-an-hour room: a room size worked out at about one air change an hour, roughly a fifth of the rate behind AHAM’s room size. The bestseller in the chart, the Levoit Core Mini, says it cleans 34 m² once an hour. At 4.8 changes an hour the same machine covers 7.1 m².
A purifier in a room bigger than its 4.8-rate size still cleans the air, only more slowly. What a buyer cannot do is compare two listings when one quotes its room at one change an hour and the other at two, and most never say which. Only 15 of the 37 room purifiers in the chart print a CADR anywhere on the listing, and one that does not, from VEWIOR, still claims “a high-performance CADR rating”. Coway’s Airmega 50 is the only one of the 37 that states the ceiling height behind its room size.
At the far end, OUNEDA’s ZY3866G says it refreshes 2,300 square feet up to three times an hour. With a 2.4 m ceiling that would take a CADR of about 1,540 m³/h, nearly three times the 520 m³/h of the Philips 3200, and the listing gives no CADR.
What else is in the chart
13 of the 50 bestsellers are not filter air purifiers: two replacement filters, four “magic dust boxes”, three plug-in ionisers, a car air-conditioning spray, a carbon odour bag and two ozone generators advertising rooms of 320 m² and 500 m². The US Environmental Protection Agency says no federal agency has approved ozone generators for use in occupied spaces, and that at levels safe to breathe, ozone does little to clean indoor air. One of the two listings tells buyers to ventilate the room for at least 30 minutes after each cycle.
The eight air purifiers worth buying
Listed from the smallest room to the largest at 4.8 air changes an hour, with prices as read on 10 September 2026. Each verdict ends with the source it rests on and the thing that source could not settle.
Levoit Core Mini
The bestsellerNumber one in Amazon UK’s air purifier chart on 10 September 2026, and the cheapest here at £49.99. Levoit says it cleans 34 m² once an hour and prints no CADR, so that statement is all there is to work from: at 4.8 air changes an hour the same output covers 7.1 m², a small bedroom. It is listed at 7 watts, which is 4.4p a day running flat out at the October 2026 cap.
The catch: Per square metre at 4.8 changes an hour it is the dearest of the eight at £7.06. A genuine Core Mini-RF filter costs £21.99, 44% of the purifier’s price, and Levoit’s filter listing does not say how often to change it.
No CADR published · 34 m² at 1 change an hour · 7.1 m² at 4.8 · 7 W · 16.5 × 16.5 × 26.4 cm · £49.99 on 10 September 2026
Behind this verdict: Levoit’s Amazon UK listings for the purifier and its Core Mini-RF filter, read 10 September 2026. The 7.1 m² is our arithmetic on Levoit’s own once-an-hour figure. With no CADR on the listing, nothing independent sits behind the 34 m².
As an Amazon Associate I earn from qualifying purchases. (paid link)
Coway Airmega 50
Budget, working shownThe cheapest pick that publishes a CADR, 120 m³/h, and the only listing among the 37 room purifiers in the chart that says what ceiling height its room size assumes. Coway says it gives one full air change every 30 minutes in rooms up to 25 m² with a 2.4 m ceiling. At 4.8 changes an hour that is 10.4 m², which works out at £5.76 per square metre.
The catch: We found no genuine Coway replacement filter on Amazon UK on 10 September 2026, only compatible ones from other sellers, and the listing gives no wattage.
CADR 120 m³/h · 25 m² at 2 changes an hour · 10.4 m² at 4.8 · 17 × 17 × 32 cm · £59.97 on 10 September 2026
Behind this verdict: Coway’s Amazon UK listing and an Amazon UK search for its replacement filter, both on 10 September 2026. Without a filter price, an interval or a wattage, the cost of keeping it running is unknown.
As an Amazon Associate I earn from qualifying purchases. (paid link)
Philips 600 Series
Best for bedroomsA CADR of 170 m³/h cleans a 14.8 m² bedroom 4.8 times an hour. Philips states a maximum draw of 12 watts, 7.6p a day flat out, and 19 dB in sleep mode. Its original filter costs £24.99 and Philips says it lasts up to 12 months, so three years of filters is at least £49.98.
The catch: The 44 m² in the title is three times the room it covers at 4.8 changes an hour, and at £99.99 it costs £6.78 per square metre on that basis, more than the Blueair or the DREO.
CADR 170 m³/h · 44 m² advertised · 14.8 m² at 4.8 · 12 W · 24.3 × 23.7 × 34.1 cm · £99.99 on 10 September 2026
Behind this verdict: Philips’ Amazon UK listings for the purifier and its original 600 Series filter, read 10 September 2026. The 19 dB sleep-mode figure is Philips’ own and names no distance.
As an Amazon Associate I earn from qualifying purchases. (paid link)
Blueair Blue Pure 511
States its 4.8 roomOne of the few listings that gives the fast figure next to the slow one: 16 m² in about 12.5 minutes, which is 4.8 changes an hour, or 38 m² in 30 minutes. On its £84.00 price that is £5.25 per square metre at 4.8 changes an hour, the third lowest of the eight. Blueair says it runs at 24 dB on low.
The catch: Blueair says to replace the £25 filter every six months. Over three years that is £125 in filters, more than the purifier costs, and the listing prints no CADR or wattage.
No CADR published · 16 m² at 4.8 changes an hour (stated) · 38 m² at 2 · 20 × 20 × 34 cm · £84.00 on 10 September 2026
Behind this verdict: Blueair’s Amazon UK listings for the purifier and its HEPASilent replacement filter, read 10 September 2026. Without a published CADR, the 16 m² rests on Blueair’s own timing claim.
As an Amazon Associate I earn from qualifying purchases. (paid link)
DREO HAP008S
AHAM claim on the listingThe listing says this purifier is AHAM Verifide and gives both numbers: a 196 m³/h CADR covering up to 79.52 m², and 4.8 changes an hour in 16.54 m². DREO’s own comparison table labels the bigger coverage figure as one air change an hour. With our 2.4 m ceiling the 4.8-rate room is 17.0 m², which at £84.99 is £5.00 per square metre, the second lowest here.
The catch: The listing quotes 24 dB in one place and 18 dB in another for its quietest setting, and its £24.99 replacement filter comes with no stated interval.
CADR 196 m³/h · 79.52 m² at 1 change an hour · 17.0 m² at 4.8 · 23.4 × 23.4 × 36.1 cm · £84.99 on 10 September 2026
Behind this verdict: DREO’s Amazon UK listings for the purifier and its 338/338S replacement filter, read 10 September 2026. We did not check AHAM’s Verifide directory, so the certification is the seller’s claim.
As an Amazon Associate I earn from qualifying purchases. (paid link)
Philips 900 Series
Mid-size roomsA CADR of 250 m³/h covers a 21.7 m² room at 4.8 changes an hour, through a HEPA and active carbon filter. Philips says it draws 23 watts at maximum, 14.5p a day flat out, and that its £39.99 original filter lasts up to a year.
The catch: The 65 m² in the title is three times the 4.8-rate room, and the listing’s product details give 21 watts where its bullet points give 23.
CADR 250 m³/h · 65 m² advertised · 21.7 m² at 4.8 · 23 W · 24 × 23.8 × 36.4 cm · £139.99 on 10 September 2026
Behind this verdict: Philips’ Amazon UK listings for the purifier and its original 800 and 900 Series filter, read 10 September 2026. A year is Philips’ best case; how fast a filter clogs depends on the room.
As an Amazon Associate I earn from qualifying purchases. (paid link)
Winix 5500-2
Cheapest per square metreThe most clean air for the money among the eight. A CADR of 390 m³/h cleans a 33.9 m² room at 4.8 changes an hour, so at £159.00 it is £4.70 per square metre, the lowest here. The listing says it is certified by Allergy UK, ECARF and AHAM, and Winix recommends changing its £53.37 Filter H every 12 months.
The catch: It stands 59.9 cm tall, and the listing’s bullet points say 23 watts on high while its product details say 70. A filter a year adds £106.74 over three years.
CADR 390 m³/h · 99 m² advertised · 33.9 m² at 4.8 · 20.8 × 38.1 × 59.9 cm · £159.00 on 10 September 2026
Behind this verdict: Winix’s Amazon UK listings for the 5500-2 and its genuine 116130 Filter H, read 10 September 2026. Because of the wattage conflict, running it flat out costs either 14.5p or 44.2p a day, and we cannot tell which.
As an Amazon Associate I earn from qualifying purchases. (paid link)
Philips 3200 Series
Open-plan roomsA CADR of 520 m³/h, the highest of the eight, for a 45.1 m² room at 4.8 changes an hour. Philips says it draws 36 watts at maximum, 22.7p a day flat out, and runs at 15 dB(A) at its quietest.
The catch: At £260.00 it is the dearest purifier here and its original filter is the dearest too at £69.99, which Philips says lasts up to a year. The 135 m² in the title is three times the 4.8-rate room.
CADR 520 m³/h · 135 m² advertised · 45.1 m² at 4.8 · 36 W · 28.5 × 28.5 × 52 cm · £260.00 on 10 September 2026
Behind this verdict: Philips’ Amazon UK listings for the purifier and its original 3200 Series filter, read 10 September 2026. The 15 dB(A) is Philips’ own figure and names no distance.
As an Amazon Associate I earn from qualifying purchases. (paid link)
How to choose one
Start with the CADR. Divide it by 11.5 and you have the floor area in square metres it can clean 4.8 times an hour under a 2.4 m ceiling. If a listing gives no CADR, look for a stated time or rate for a stated room, as Blueair and Coway give, and do the same sum. If it gives neither, the room size cannot be checked.
Then price the filter before you buy the machine. The genuine filters for our eight picks ran from £21.99 to £69.99 on 10 September 2026, and the intervals makers give ran from six months to a year, with two brands giving none. Over three years the filters can cost more than the purifier, as they do on the Blueair.
Common questions
What size air purifier do I need?
Work from the CADR rather than the room size on the box. Divide the CADR in cubic metres an hour by 11.5 to get the floor area, in square metres, that it can clean 4.8 times an hour under a 2.4 m ceiling, the rate AHAM uses for the room size on its seal. A 170 m³/h purifier suits about 14.8 m². Of the 25 Amazon UK bestseller listings where the rate could be worked out on 10 September 2026, 22 advertise a room size based on two air changes an hour or fewer.
What is CADR on an air purifier?
Clean air delivery rate: the volume of cleaned air a purifier delivers, given in cubic metres an hour or cubic feet a minute. It is the one figure that lets you check a room size. Only 15 of the 37 room purifiers in Amazon UK’s bestseller chart on 10 September 2026 print one anywhere on the listing.
How much do air purifier filters cost?
For our eight picks, a genuine replacement filter cost £21.99 to £69.99 on Amazon UK on 10 September 2026. The interval matters as much as the price. Blueair says to replace the Blue Pure 511’s £25 filter every six months, which is £125 over three years on an £84 purifier, while Philips says its 600 Series filter lasts up to 12 months.
How much does an air purifier cost to run?
Very little on the listed wattages. At the October 2026 cap of 26.32p per kWh, the Levoit Core Mini at its listed 7 watts costs 4.4p a day running flat out for 24 hours, and the Philips 3200 at 36 watts costs 22.7p. Few people run one at full speed all day, so treat those as the ceiling.
Are ozone generators air purifiers?
They are sold alongside them. Two ozone generators were in Amazon UK’s air purifier bestseller chart on 10 September 2026. The US Environmental Protection Agency says no federal agency has approved ozone generators for use in occupied spaces, and that at levels safe to breathe, ozone does little to clean indoor air.
Fighting damp as well as dust? Our dehumidifier guide prices each litre of water removed, and the UK running cost index puts other household appliances on the same cap rate.
Sources
- AHAM, Portable Air Cleaners and Air Changes per Hour (white paper, October 2021: suggested room size based on 4.8 air changes an hour, 8-foot ceiling)
- US EPA, Ozone Generators that are Sold as Air Cleaners (last updated 19 February 2026)
- Ofgem, Energy price cap unit rates and standing charges (average direct debit electricity 26.32p per kWh from 1 October to 31 December 2026)
- Amazon.co.uk Best Sellers: Air Purifiers, all 50 listings read in full on 10 September 2026
Prices checked on Amazon UK on 10 September 2026 and change often. Look Into earns a commission on qualifying purchases made through the links above, at no extra cost to you.