The 5 best air purifiers, matched to real room size

Coway Airmega AP-1512HH

The right pick for most bedrooms and mid-size living rooms. The box says 1,748 sq ft, but that is one air change per hour. At the 4.8 changes per hour that allergy and smoke guidance is based on, it fits a room of about 365 sq ft.

Key specs (from the manufacturer listing):

• Maker claims 1,748 sq ft in 60 minutes (one air change)
• Our sizing: about 365 sq ft at 4.8 air changes per hour
• Washable pre-filter, odor filter, HEPA filter, plus an ionizer you can switch off
• Auto mode with a particle sensor and colored air quality light

What owners say (our summary of Amazon reviews):

• They like: Owners say it cuts dust and pet dander, runs quietly, and that replacement filters are affordable.
• They complain about: Odor removal gets mixed reviews. So does long-term durability, though many report years of use.

Good:

• Auto mode keeps it quiet until it is needed
• Long track record. This model has been sold for over a decade
• Pre-filter is washable

Watch out for:

• No app
• The ionizer is optional. Leave it off if anyone in the home is sensitive

Levoit Vital 200S-P

Get this for an open living room or a primary bedroom. It is the strongest unit here, advertised for 1,875 sq ft in an hour, which works out to about 390 sq ft at a proper 4.8 air changes. It is AHAM Verifide and has app control.

Key specs (from the manufacturer listing):

• Maker claims 1,875 sq ft in 60 minutes
• Our sizing: about 390 sq ft at 4.8 air changes per hour
• AHAM Verifide (independently verified clean air delivery rate)
• App and voice control

Good:

• Fits open living rooms and primary bedrooms
• Independent performance verification
• Scheduling from your phone

Watch out for:

• Bigger and louder on high than the bedroom units
• App requires 2.4 GHz WiFi setup

Levoit Core 300

Buy it for a small bedroom or office. Skip it for a living room, whatever the box says. This is the best known small purifier. Its verified smoke CADR is 143 CFM, which by the AHAM rule fits a room of about 220 sq ft.

Key specs (from the manufacturer listing):

• AHAM Verifide CADR: 143 CFM smoke, 153 CFM dust
• Our sizing: about 220 sq ft (smoke CADR times 1.55)
• 56W motor
• Uses Levoit Core 300 replacement filters

What owners say (our summary of Amazon reviews):

• They like: Owners say it is quiet, helps with allergies and smoke, and that replacement filters are reasonably priced.
• They complain about: The review summary we read was mostly positive. The real limit is size: it is a one-room unit.

Good:

• Small and quiet on low
• Replacement filters are easy to find
• Independent performance verification

Watch out for:

• One per room. It will not clean a whole apartment
• No air quality sensor on the base model

GermGuardian AC4825E Tower

Good for a small bedroom where floor space is tight. It is a slim 22 inch tower, and the listing itself gives a realistic size: 153 sq ft at 4.8 air changes per hour.

Key specs (from the manufacturer listing):

• Maker states 153 sq ft every 12.5 minutes (4.8 air changes per hour), 743 sq ft once per hour
• HEPA filter, three speeds
• CARB certified, ETL certified and zero ozone verified per the listing

What owners say (our summary of Amazon reviews):

• They like: Owners with allergies report less sneezing and coughing and a cleaner smell in the room.
• They complain about: Noise. Some find it reasonably quiet. Others find the higher speeds too loud for sleep.

Good:

• Small footprint
• Sizing on the listing is realistic
• Sold for many years, so filters are widely stocked

Watch out for:

• Small rooms only
• Owners are split on noise at higher speeds

Afloia Large Room Purifier

A budget option for a mid-size room, if you are fine with a lesser-known brand. The maker publishes a useful number: four air changes per hour in 374 sq ft. At 4.8 changes that is about 310 sq ft.

Key specs (from the manufacturer listing):

• Maker states 4 air changes per hour in 374 sq ft, 1,500 sq ft in an hour
• Our sizing: about 310 sq ft at 4.8 air changes per hour
• Washable pre-filter, timer, night light

What owners say (our summary of Amazon reviews):

• They like: Owners report a noticeable difference within a day and call it very quiet.
• They complain about: It is a lesser-known brand, so there is less long-term feedback than for Coway or Levoit.

Good:

• Quiet, according to owners
• Timer settings of 2, 4, 8 and 16 hours

Watch out for:

• The listing contradicts itself. Its spec table shows a CADR of 140 cubic meters per hour, about 82 CFM, which by the CADR rule fits only about 130 sq ft. If that number is the true one, treat this as a small-room unit
• No independent AHAM verification on the listing
• Lesser-known brand, so check that replacement filters are in stock before you buy