How to choose an air purifier: 2026 buying guide

You need a purifier whose maker-stated room size at 4.8 air changes an hour is at least the floor area of your room. Measure the room (length times width, in square feet) and use that number, not the large "cleans up to 1,800 sq ft" figure on the front of the box.

Makers print two very different room sizes for the same machine:

• Room size at 4.8 air changes an hour. The room the purifier can filter almost five times every hour. AHAM, the trade group that certifies clean air delivery rates, uses this basis for its suggested room size. Levoit prints it as "(4.8 ACH)", Blueair as "Recommended room size" next to "Air changes per hour (ACH) 4.8", and Winix as "AHAM Verified Room Size".
• Room size at 1 air change an hour. The room the purifier filters once an hour. It is about 4.8 times larger, which is why it makes the headline. Coway prints coverage at 1, 2 and sometimes 4 air changes an hour; Levoit and Winix print it next to the AHAM figure.

We use the 4.8 figure for every purifier. Where a maker only prints the 1, 2 or 4 air-changes figure (most Coway models), we convert it: area times air changes, divided by 4.8. For example, Coway states the Airmega 450 cleans "3,285 ft²" at 1 air change an hour, which works out to 684 sq ft at 4.8.

AHAM gives a simple rule on its directory page: "You'll always want a unit with a tobacco smoke CADR at least 2/3 your room's area." It also says: "If you have ceilings higher than 8′, you'll want an air cleaner rated for a larger room."

The room options in the finder are floors, so each one shows purifiers rated for at least that much floor area:

Of the 31 air purifiers we catalogued (as of October 22, 2026), room sizes at 4.8 air changes an hour ran from 169 sq ft (Coway Airmega 100) to 684 sq ft (Coway Airmega 450).

If it's for a bedroom or home office → measure it; most are 120 to 200 sq ft, so "Up to 250 sq ft" leaves some room to spare. If it's for a living room → choose "Up to 350 sq ft" or larger. If the room is open to a kitchen or hallway → add the connected area, or choose "Up to 500 sq ft". If your ceiling is higher than 8 feet → go up one option, as AHAM advises.

See purifiers for rooms up to 250 sq ft · See purifiers for rooms up to 500 sq ft · Related list: Air purifiers for large rooms

CADR (clean air delivery rate) is how many cubic feet of filtered air a purifier delivers per minute, measured separately for smoke, dust and pollen particles. You don't need to compare it separately if you choose by room size, because the 4.8 room size comes from the smoke CADR.

Most makers list three CADR figures (smoke, dust, pollen). We record the smoke figure where the maker names it, because it is the one AHAM's room-size rule uses. Levoit prints a single "CADR" figure on most of its pages without naming the particle; we record that figure as Levoit gives it. In our catalogue, CADR ran from 108 CFM (Coway Airmega 100) to 439 CFM (Coway Airmega 450). Three models list no CADR on the page we used (Levoit Vital Pet Pro, Winix C610 and Winix 9800), so we show it as not stated.

Our budget options use the price the manufacturer's own US store charged when we checked (October 19, 2026; Winix and Medify on October 22, 2026), not a retailer's price and not the crossed-out "was" price. On 4 of the 31 purifiers, the maker's store charged less than its own list price when we checked, so we budget by the price the store actually charged. Between our two checks, six Winix models went back to their list price on Winix's store. Prices change often, so check the current price before you buy.

The budget options are ceilings, so "Under $400" also shows everything under $300:

• Under $300: 25 of the 31 models, in every room option. Three are rated for 500 sq ft or more: the Blueair Blue Pure 311i+ Max, the Medify MA-50-V3.0 and the Levoit Core 600S-P.
• Under $400: 29 models, adding the Coway Airmega 350, the Blueair DustMagnet 5440i and the Winix D480 and 9800.
• No limit: all 31, adding the Levoit EverestAir-P and the Coway Airmega 450.

Running costs matter too: every purifier here uses a replacement filter, and the maker sells it separately. Makers sell several filter types for the same model (an original filter, a pet filter, a smoke filter), so we don't put one filter price on each product. Check the maker's filter page for the model you choose.

If you need a bedroom purifier → "Under $300" covers most of what we catalogued. If the room is 500 sq ft or larger → you can stay under $300, but there were only three choices there when we checked. If you want the largest room size we catalogued → the Coway Airmega 450 (684 sq ft) sat above $400 on Coway's store when we checked.

See purifiers under $300 · See large-room purifiers under $300

These are the names makers give their main filters, and they are not interchangeable labels: we record exactly the name each maker uses and make no claim about what any filter removes. If you want a filter the maker calls True HEPA, ask for it in the finder; if you only want one the maker calls HEPA in some form, choose the broader option.

Here is how the 31 purifiers in our finder break down by the name on the maker's page:

A few notes on the names:

• Winix lists "True HEPA" in the spec table of every model here.
• Coway lists a "HEPA Filter" (or "HEPA" inside its Max2 filter) in each spec table.
• Levoit uses "HEPA-grade" for some filters and "HEPA filter" on its newer Eleva models; several Levoit Core pages don't name the filter type at all, so we show it as not stated rather than guess.
• Medify lists "HEPA" in the filter configuration of the MA-50-V3.0.
• Blueair calls its approach HEPASilent, which it describes as combining "electrostatic and mechanical filtration".

In our catalogue, "True HEPA" is the name Winix uses; Coway, Medify and Levoit say "HEPA" or "HEPA-grade", and Blueair says "HEPASilent". We report each name as the maker writes it and do not rank the names.

If the filter name matters to you → choose "Yes, True HEPA" in the finder; every match here is a Winix. If any filter the maker calls HEPA will do → choose "True HEPA or a filter the maker calls HEPA", which adds Coway, Medify and the Levoit Eleva models. If you'd rather choose by room size, quiet and app → leave this question at "No preference".

See purifiers with a True HEPA filter

For a bedroom, look for a lowest setting under 25 dB; under 22 dB is the quietest group we found. The figure is the lowest noise level the maker states, usually on the lowest fan speed or in sleep mode.

Makers don't say how far from the unit or in what room they measured, so treat 1 or 2 dB as a tie. In our catalogue the lowest stated levels ran from 19 dB (Coway Airmega Mighty2) to 31 dB (Blueair DustMagnet 5440i):

• Under 22 dB: 8 models, five of them Coway (Airmega Mighty2, Mighty2 Mini, 150, 100 and 350), plus the Levoit Eleva 300X and Vital Pet Pro and the Medify MA-50-V3.0.
• Under 25 dB: 26 models.
• 25 dB or more: 6 models, including the Winix A231 and D480 (25 dB) and the Blueair DustMagnet 5440i (31 dB).

A purifier is quietest on its lowest speed, and it moves the least air there. If you run it on low all night, a purifier rated for a larger room than yours moves more air at the same noise level.

If it runs next to your bed → choose "Under 22 dB" or "Under 25 dB". If it's for a living room you're not in at night → noise matters less than room size.

See quiet purifiers for bedrooms · Related list: Quiet air purifiers for bedrooms

You need app control only if you want to change settings, set schedules or see the purifier's air quality readings from your phone. Most purifiers here also have an auto mode on the unit itself.

16 of the 31 purifiers we catalogued have app control stated by their maker: Levoit's models with an "S" or the Eleva, EverestAir and Vital Pet Pro (VeSync app), Blueair's "i" models (Blueair app), Coway's MightyS AP-1512HHS (IoCare+ app), and four Winix models (Winix Smart App). The other 15, including the Medify MA-50-V3.0, don't mention an app on their page, so we show it as not stated.

If you want schedules or voice-assistant control → choose "Yes, app control". If you'd rather not install another app → leave it at "No preference"; the buttons on the unit do the same basic jobs.

See purifiers with app control

Choose a carbon filter if you want the purifier to take on household odors such as cooking smells; makers add a carbon layer for that. The carbon layer doesn't change the room size rating, which comes from the particle filter.

25 of the 31 purifiers we catalogued state a carbon filter or carbon layer, under names like "Activated Carbon Filter" (Levoit), "Max2 Filter (Activated Carbon + HEPA)" (Coway), "Particle & Carbon" (Blueair), "AOC Carbon" (Winix) and "Active Carbon Composite" (Medify). Coway's Airmega 100, 150, 200M and Mighty AP-1512HH name a "Deodorization" filter without saying carbon, so we show carbon as not stated for them.

See purifiers with a carbon filter

• The "cleans up to ... in 1 hour" number. It's the 1-air-change figure, about 4.8 times the room size we use. Two purifiers with the same 1-hour figure have the same 4.8 figure, so it adds nothing once you know the room size.
• Number of "stages". Makers count a washable pre-filter, a carbon layer and the main filter differently. A "4-stage" and a "3-stage" model can hold the same filter types.

• Buying by the headline square footage. Check the 4.8 air-changes figure, or the AHAM figure, on the spec table.
• Forgetting connected spaces. An open kitchen or hallway is part of the room the purifier has to filter.
• Running it on low all the time. If you'll keep it on the quietest setting, choose one rated for a room larger than yours.
• Ignoring the filter. Check that the maker sells the replacement filter, and its price, before you buy.

• Air purifiers for large rooms: rated for 500 sq ft or more at 4.8 air changes an hour.
• Quiet air purifiers for bedrooms: under 22 dB on the lowest setting.

Why does your room size look smaller than the box?

Because we use the room size at 4.8 air changes an hour, AHAM's basis, and the box often shows the room size at 1 air change an hour, which is about 4.8 times larger. Both come from the same machine; ours is the one you compare against your room.

Why are some Coway room sizes calculated?

Coway's spec tables for models like the Airmega 350 and 450 state coverage only at 1 and 2 air changes an hour. We divide the 1-air-change area by 4.8 and show the working next to the value. Where Coway prints the 4.8 figure itself (Airmega 150, 200M, Mighty AP-1512HH, MightyS), we use Coway's figure.

Which price do the budget options use?

The price on the manufacturer's own US store when we checked (October 19, 2026; Winix and Medify on October 22, 2026). When a maker shows a crossed-out list price next to a lower one, we use the lower price the store charges. We don't show live prices, and prices change often, so check the current price before you buy.

Why isn't Dyson, Honeywell or IQAir in the finder?

We only use specs and prices from each manufacturer's own site. Dyson's and Honeywell's US sites refused our automated reads, and IQAir's site returned "too many requests", so we couldn't verify their specs and prices. We don't fill gaps from retailer pages.

Do you say which purifier is healthiest?

No. We report what each maker states (room size, CADR, filter name, noise, app control and carbon) and match it to your answers. We don't make claims about health or what any purifier removes from the air.

Written with AI assistance from manufacturer specifications; reviewed and approved by the site owner. We don't test products hands-on. How we choose

Results are ordered by how well each model fits your answers. When two models fit equally, the one with more features stated by its maker comes first, then the one with the lower price on the maker's own store, then a fixed catalogue order. Commissions never affect the order.

"Catalogued" means the 31 portable air purifiers we catalogued for this category from manufacturer sites as of October 22, 2026 (Levoit, Coway, Blueair, Winix and Medify, rated from 169 to 684 sq ft at 4.8 air changes an hour), not the whole market. Each product's source links appear with its specs. Pages quoted in this guide:

• AHAM Verifide, directory of air cleaners
• Coway Airmega 450
• Levoit Core 300S-P
• Levoit Eleva 300X
• Blueair Blue Pure 311i Max
• Blueair Blue Pure 311i+ Max
• Winix 5520
• Medify MA-50-V3.0