How we choose

We pick products from published specs, retailer prices and owner-reported problems, not from who pays us. We don’t lab-test every product, and we say so whenever we haven’t used one ourselves.

Our method in four steps

1. Start from what matters for how the product is used, and write that down before looking at any model.
2. Compare manufacturer specs side by side, not marketing claims.
3. Check prices at several retailers and show the date we checked.
4. Revisit the list when prices move or a model is replaced.

What we don’t do: lab-test every product. When we have used one ourselves, the review says so.

What we compare

Each category has a fixed set of lead specs, chosen for what changes the result at home: for example, clean air delivery rate, noise on the lowest setting, filter grade and the cost of replacement filters for air purifiers. Every product in the category is compared on the same specs, in the same order.

• Room size from CADR, not from the box. We work out the room a purifier suits from its clean air delivery rate (CADR): the CADR in m³/h divided by 12, which gives about five air changes an hour in a room with a 2.4 m ceiling. Makers’ own room sizes assume fewer air changes, so they come out larger. Our guide to what size air purifier you need shows the maths.
• Which test a CADR comes from. Makers test to different standards, and many don’t say which: Philips names the Chinese GB/T 18801, while several brands give a CADR with no standard at all. We say which one applies where the maker does. Where a maker publishes no CADR at all, as Dyson doesn’t, we show it as not published rather than estimate one.
• Filter class as stated. We list a filter as H13 or H14 only when the maker names the class. “True HEPA” and similar labels are not a class, so those filters show as HEPA-type.
• Filters and running costs. Every product page gives the main filter’s part number and how often the maker says to change it, and the power drawn on the lowest and highest settings where the maker publishes them. Our filter finder lists them by model.

How we score

Our score is editorial, out of 10, and based on that research. It is never shown as stars, because stars read as customer reviews. A sound, current purifier with a published CADR and a classed HEPA filter starts at 7.5. We then move it for value and running costs within its class, for the filter grade, CADR evidence and warranty, for features that matter in use (noise on the lowest setting, a sensor and auto mode, the app, carbon for smells, how easy filters are to buy), and by up to a point either way for problems or praise that recur in owner reviews.

What owners say

Where we summarise what owners say, we read a sample of owner reviews and forum posts by hand, note each point in our own words, and count only what we read. The summary names the sources and how many reviews it is based on, and a person approves it before it appears. We match reviews on the model number, and we leave out reviews that sites which refuse our reader collected, even when another shop shows them.

Health claims

An air purifier filters particles out of the air. We say what a filter captures, as the maker states it, and never that a purifier treats, prevents or relieves asthma, allergies, hay fever or any other condition. Where health comes up, we point to the official guidance from the NHS, Allergy UK and Asthma + Lung UK, and to a pharmacist or GP for symptoms.

What we don’t do

• We don’t lab-test every product or claim hands-on testing that didn’t happen.
• We don’t accept payment to include, rank or remove a product.
• We don’t show a price as current once it is out of date: older prices say when they were last checked.
• We don’t copy retailer, manufacturer or review text: everything is in our own words, with sources named on each product page.

How often we update

Prices are checked by hand at least once a week until retailers send us price feeds, which update daily, and every price shows the date it was checked. Guides and picks are reviewed every six months, or sooner when a model is replaced. The “Updated” date on a page changes only when its content or prices changed, and each page notes what changed.

How we use AI

We use AI tools to help draft pages and to summarise large sets of owner reviews. Specs come from manufacturers and prices from retailers. Some scene photos of rooms are AI-generated; they never show a product, and products appear only in real photos with a recorded licence or as our own drawings.

How we make money

Retailers whose affiliate programmes accept us pay us a commission when you buy through our links. Commission never decides what we recommend or the order we list products in. Our affiliate disclosure always shows who pays us today.