What size air purifier do you need?
Tell us about the room. We'll tell you the size of purifier it needs, and show ones we rate in that size.
Find your size in 2 questions
The room decides the size. If it has to be quiet, go one size up.
How we work out the size
Look at the clean air rate, not the box. A purifier's CADR says how much clean air it puts out. For allergies, you want the air in the room cleaned about five times an hour, which works out at a CADR of about two-thirds of the floor area: 100 CFM for a 150 sq ft bedroom, 230 CFM for a 350 sq ft living room.
Between two sizes? Go bigger. A bigger purifier cleans the same room on a lower, quieter speed. A small one has to run flat out, which is when it gets loud.
Open-plan counts as one room. Air moves freely through an open kitchen, dining and living space, so measure all of it.
How we reached this verdict
We compared independent expert reviews with the manufacturer's specifications, then checked it's sold at a major retailer where you live. We don't test products ourselves.
Sources: RTINGS, RTINGS: Levoit Vital 200S, TechRadar, Expert Reviews, HouseFresh: Winix 5510, manufacturer specifications.