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Where to place an air purifier
Updated
Put the purifier in the room where you spend the most hours, which for most people is the bedroom. Give it open space on all sides, keep it away from curtains and corners, and close the door. Then leave it running.
The short rules
- One room at a time. A purifier cleans the room it is in. It does not push clean air down a hallway. Sizes on this site assume one closed room.
- Open air around it. The intake and the outlet both need to breathe. Behind a couch, under a desk or tight in a corner, it just recycles the same pocket of air. Check your manual for the clearance the maker asks for.
- Near the source, if there is one. By the window that leaks smoke, near the litter box, or beside the door to the garage.
- Not in a damp spot. Keep it out of bathrooms and away from humidifiers. Damp air shortens filter life.
- Doors and windows closed. An open window brings in new particles faster than a home purifier can remove them.
Floor or table?
Either works if the air paths are clear. Larger units belong on the floor. A small, light unit can sit on a dresser or a sturdy table, which also keeps it away from pet hair and small children. Make sure it is stable and the cord is not a trip hazard.
| Model | Size per listing (inches) | Weight | Good spot |
|---|---|---|---|
| Levoit Core 300 | 8.7 x 8.7 x 14.2 | 7.9 lb | Floor, nightstand or dresser |
| GermGuardian AC4825E | 6.75 x 10.25 x 22 | 8.55 lb | Floor, in a narrow gap with the front clear |
| Coway Airmega AP-1512HH | 16.8 wide, 18.3 tall, 9.6 deep | 12.3 lb | Floor, along a wall with the front open |
| Levoit Vital 200S-P | 15.6 x 8.5 x 19.8 | 13.2 lb | Floor, in the open part of a large room |
In a bedroom
A few feet from the bed is fine. You do not need it aimed at your face. If the display bothers you, the Levoit Core 300 listing says its display lights can be turned off, and the Coway Airmega AP-1512HH listing says its air quality light can be turned off. The caveat with the Core 300 is that it has no sensor, so pick a speed you can sleep through and leave it there.
In a large room
Past about 390 sq ft, use two units at opposite ends. Our large living room page has the numbers.
How long to run it
All day. A purifier only works while it is running, and particles build back up within hours of turning it off. If noise or power use bothers you, run it on auto or low instead of switching it off. Power use on low is small. See running costs.
If you have been out with the purifier off, run it on high with the door closed for a while before bed, then drop it to a quiet speed.
Placement cannot fix the wrong size
Perfect placement does not make a 220 sq ft purifier clean a 500 sq ft room. Size it first.
Check any other model with the room size calculator, or see all five picks on the best by room size page.
An air purifier reduces airborne particles. It is not a medical device, and nothing here is medical advice. If anyone in your home has asthma, allergies or another condition, follow your doctor's guidance.