Home/Buyer's guide
How to choose an air purifier
Get the size right first. Then check the filter, then the running cost.
Six things to check
- Ignore the coverage on the box.It assumes one air change an hour. For smoke or pollen, divide it by four, or use the size calculator.
- Compare CADR.Clean air delivery rate is the speed number. Be wary of any unit over $300 that doesn't publish it.
- H13 or H14.H13 suits most homes. H14 is worth it for asthma or bad hay fever. “HEPA-type” promises nothing. HEPA explained.
- Carbon for smoke.HEPA catches particles. Only activated carbon deals with smoke smell, and more is better.
- Price the filters.They cost $65 to $130 a year on our list. Compare three-year costs.
- Buy in winter.Prices tend to be lowest from May to July.
Getting the most from it
- Put it where you spend time: the bedroom at night, the living area by day.
- Keep it clear of walls, corners and curtains.
- Close the door. It cleans a room, not the whole house.
- Leave it on auto, and turn it up on smoke days.
- Vacuum the pre-filter monthly over summer.
- Keep a spare filter. They can sell out when a big fire hits.
Filter reminders
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