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Waking up unrefreshed usually gets blamed on the sleep. Often it is the air in the room you slept in.
These three differ by a third in coverage, by a factor of three in power draw, and by about £70 on the shelf. Start with the room, not the badge.
| Blueair 311i Max | Blueair 511i Max | Levoit Vital 200S-P | |
|---|---|---|---|
| CADR, pollen | 365 cfm | 174 cfm | 250 cfm |
| Rated room, 4.8 ACH | 41 m² | 22 m² | 36 m² |
| Noise | 23–50 dB | 19–48 dB | 23–54 dB |
| Power draw | 32 W | 17 W | 50 W |
| US list price | $229.99 | $139.99 | $189.99 |
| Weak point | Ioniser cannot be switched off | One bedroom only, despite the listing | 50 W, and loudest at full speed |
All three discount through the year and rarely at once — start with the current price.
CADR365 pollen · 314 dust · 283 smoke cfmRoom41 m² at 4.8 ACHNoise23–50 dB · QuietMarkPower32 WUS list$229.99
Most people buy one machine, and it ends up in the room where the evening happens. 41 m² covers that room in most houses, which is why this is the default rather than the cheapest.
It manages that without the noise you would expect. HEPASilent charges the particles before the filter catches them, so the fan turns slowly, and 23 dB on the low setting earned QuietMark certification.
Thirty-two watts is modest for that much airflow. Filters cost a US list of $44.99 and last up to nine months.
The drawback: the electrostatic stage cannot be turned off. It emits only trace ozone, within safety limits, but several rivals fit a switch and Blueair does not. Where someone in the house has asthma, that missing switch is reason enough to look at a purely mechanical unit.
Check today's price on AmazonBlueair Blue Pure 311i Max →
Read the full Blue Pure 311i Max review
CADR174 pollen · 159 dust · 153 smoke cfmRoom22 m² at 4.8 ACHNoise19–48 dB · QuietMarkPower17 WUS list$139.99
On US list this is $90 below the pick above, and it runs on half the electricity. For a single bedroom nothing here matches it on cost.
Nineteen decibels is the lowest floor in the group, eleven below a quiet bedroom's own background. At 1.9 kg you can carry it to whichever room needs it that week.
It is also the only unit here holding CARB Zero Ozone certification, below 5 parts per billion, despite using the same electrostatic method as its bigger sibling.
The drawback: the listing advertises 1,138 sq ft, a figure that assumes one air change an hour. Blueair's actual recommendation is 237 sq ft, about 22 m². Buy it for a sitting room on the strength of the bigger number and it will not keep up.
Check today's price on AmazonBlueair Blue Pure 511i Max →
Read the full Blue Pure 511i Max review
CADR250 cfmRoom36 m² at 4.8 ACHNoise23–54 dBPower50 WPre-filterWashableUS list$189.99
Both Blueairs are built around particles and treat odour as a secondary job. This one inverts that: Levoit sells pet, toxin-absorbing and smoke versions of the filter at a US list of $59.99 to $64.99.
The pre-filter is washable, which neither Blueair offers. With a moulting animal in the house that is the difference between rinsing a mesh and buying a replacement.
Coverage sits between the two above at 36 m², and sleep mode drops the fan and turns the display off.
The drawback: 50 watts is triple the 511i Max and the highest here, and full speed has been measured near 57 dBA — loud enough to interrupt a conversation. The three-layer filter is a single piece, so when the carbon gives out at about six months a serviceable HEPA layer goes in the bin with it.
Check today's price on AmazonLevoit Vital 200S-P →
Read the full Levoit Vital 200S-P review
Measure the room and match it to the rated area at 4.8 air changes an hour, not the larger figure on the box. CADR is the number that decides whether a purifier can keep up with your room sets out the arithmetic.
Undersizing is the usual mistake, and it hides well — the machine runs, it simply never catches up.
Two small ones, if the rooms are separate. Air does not travel between closed doors, so a purifier only cleans the room it is standing in.
Less than most people assume. At 17 to 50 watts that is roughly 150 to 440 kWh a year — what an air purifier costs to run in 2026 puts UK unit rates against those numbers.
As an Amazon Associate I earn from qualifying purchases. This post contains affiliate links. We were not given these products and were not paid to write about them.
