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Buying guide
Learn how to choose an air purifier by room volume, CADR, filtration, noise and upkeep, including what size air purifier you need.
Quick answer
Manufacturers often publish more than one room size, each tied to a different air-change rate. Core 300S, for example, lists 50 m² at two air changes per hour and 100 m² at one. Blueair Blue Pure 511 recommends around 16 m² at 4.8 air changes per hour. Use the figure that matches your room and expected use, and treat maximum sizes as the upper limit rather than a bedroom recommendation.
Clean air delivery rate (CADR) is the volume of filtered air a unit delivers. Vital 100S states 243 m³/h. WINIX ZERO Compact states 250 m³/h. Philips AC0820/10 states 190 m³/h. Blueair Blue Pure 511 states 123 cfm for pollen and dust, which is roughly 209 m³/h by standard conversion (our calculation). Core 300S does not publish a CADR in our source, so its airflow cannot be compared directly.
For the wider context on room air cleaners, see the air purifier category.
A filter's job depends on the type of pollutant and the filter stack, so check what each manufacturer lists for pre-filter, particle and any other stages. A unit that performs well for dust may not be the right choice if you need a particular kind of protection. Our sources do not support medical or health-outcome claims, so treat any health need as a question for your doctor.
A low minimum noise figure is not the same as a low sleep-mode noise level. Figures from our sources:
If noise matters at night, compare sleep-mode figures first and the top-speed range second. For model-by-model detail, see the Core 300S, Vital 100S and Zero Compact comparison.
Place the unit in open floor space, away from walls and furniture that block the intake and outlet, following each manufacturer's clearance guidance. Keep the room door closed while the unit runs if you are judging the room's clean-air time.
Replacement intervals from manufacturer sources differ: Core 300S 6–8 months, Vital 100S 8–12 months, Blueair Blue Pure 511 six months, WINIX ZERO Compact and Philips AC0820/10 twelve months. Power figures also vary: WINIX ZERO Compact 12–55 W, Blueair Blue Pure 511 16 W, Philips AC0820/10 up to 20 W. Vital 100S and Core 300S do not publish power in our source, so their running cost cannot be calculated from it.
We have no verified filter prices, so we cannot state a cost. To estimate one, use this method: filter price × replacements per year (12 ÷ interval in months) + your electricity use. Compare the totals, not the purchase prices.
Gearjury has not tested these air purifiers physically. The figures above come from manufacturer product pages consulted on 13 October 2026 and from the EPA's general guidance on room air cleaners. Where a manufacturer gives conflicting or missing figures, we say so rather than fill the gap.
| Criterion | What to check | Why it matters |
|---|---|---|
| Room size | Air-change rate behind the m² figure | Makes sizes comparable |
| CADR | m³/h or cfm, same unit for all models | Shows airflow |
| Sleep-mode noise | dB in sleep mode, not only top speed | Matters for bedrooms |
| Lights | Display dims or switches off in sleep | Affects night-time use |
| Filter interval | Manufacturer months between replacements | Drives yearly cost |
| Power | Watts by mode, if published | Affects running cost |
| Data gaps | Figures not published | Shown as — in comparisons |
Common questions
Start with the room size in square metres, then check the clean air delivery rate (CADR), which manufacturers state in m³/h or cfm. Next, check noise in the mode you will use at night, and the filter replacement interval. Our sources do not name one best model, because the right choice depends on your room and priorities.
Our sources do not document a 2/3 rule, so we do not apply one. Use the manufacturer's room size and air-change figures instead, and remember that a maximum room size is not the same as a recommendation for a quiet bedroom.
Avoid judging a unit by one headline figure. A maximum room size without its air-change rate, or a low noise figure without a matching CADR, can mislead. Check the filter replacement interval and cost, and whether sleep-mode noise is stated at all.
We have no verified prices, so we cannot give a figure. Work out the total instead: purchase price plus filter price multiplied by replacements per year, using the manufacturer's interval. Compare totals over a year, not sticker prices alone.
Our sources do not compare one large unit with several small ones, so we cannot say which is better. Check each unit's room size and CADR. If several units share one room, compare their combined output and noise rather than assuming the figures simply add up.
We make no medical or health-outcome claim for any model in this guide. If asthma affects you or someone in your home, speak to your doctor or asthma nurse before relying on an air purifier.
Keep exploring
Compare five air purifiers by manufacturer-published room coverage, particle filtration details and noise. Philips AC0820/10 is a compact-room starting point; no product here promises allergy relief.
The Levoit Vital 100S and WINIX ZERO Compact publish CADR figures in m³/h. We compare five models by manufacturer data, with room-size assumptions and missing costs made clear.
Philips AC0820/10 leads with a 19 dB(A) sleep mode in manufacturer data. Levoit, Blueair and Winix cover other bedroom needs, from small rooms to larger spaces.