A published CADR, or a sealed HEPA claim with no CADR at all

Xiaomi Smart Air Purifier 4 Compact vs Dyson Purifier Cool PC1

Do you want the numbers to compare, or the design Dyson is confident enough not to publish them?

Both purifiers use HEPA filtration, and both publish real specifications — just not the same ones. Xiaomi's page is built to be compared line by line; Dyson's leaves several of those lines blank.

Xiaomi Smart Air Purifier 4 Compact

7.0/10

Wins 5 of 8

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≈ $120

Dyson Purifier Cool PC1

8.4/10

Wins 2 of 8

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Row by row

Compared on	Smart Air Purifier 4 Compact	Purifier Cool PC1
CADR	230 m (755 ft)³/h (particulate)	Not published
Filtration standard	True HEPA, 99.97% at 0.3 micron	Sealed HEPA H13, 99.95% at 0.1 micron, tested to EN 1822
Manufacturer room rating	up to 27 m (89 ft)²	up to 23 m (75 ft)²
Noise, quietest setting	18.3 dB	Not published (only a relative "50% quieter" claim)
Doubles as a fan	No	Yes — Air Multiplier, over 250 L/s at maximum
Filter life	6–12 months, tracked on-device	Not published
Control	OLED touchscreen, Xiaomi Home app, Alexa/Google	MyDyson app, voice assistant, magnetic remote
Price	≈ 68 €	≈ 399 €
Listed on amazon.com	No	No

A tick marks the better answer on that line only. Counting ticks does not decide the page — the two verdicts below do, because these products answer different questions.

Who should take which

Smart Air Purifier 4 Compact

No amazon.com listing was found for this one. We hold references for other markets but none for the United States, so it may not be buyable here — which is the first thing to weigh against anything below.

Take the Xiaomi if you want a purifier whose entire spec sheet can be checked and compared: a real CADR, a real sleep-mode dB figure, and a tracked filter life, at roughly a sixth of Dyson's price. It suits a bedroom or small room rather than an open living space.

Purifier Cool PC1

Take the Dyson only if the combined fan-and-purifier function and the sealed-machine design matter more to you than having every spec on the page. It costs far more and publishes fewer of the standard comparison numbers — no CADR, no absolute noise rating, no filter life — so you are trusting Dyson's build reputation over a line-by-line spec comparison.

The questions that keep coming up

Why doesn't Dyson publish a CADR figure?

It isn't stated in the listings we checked across four markets. Dyson instead publishes a particle-removal percentage (99.95% at 0.1 micron, tested to EN 1822) for the sealed HEPA H13 system, which is a different kind of claim to a CADR volume figure, and the two cannot be converted into each other from the data available.

Is 'sealed HEPA H13' better than 'True HEPA 99.97%'?

They describe different things. Xiaomi's 99.97%-at-0.3-micron figure describes the filter medium's own capture rate. Dyson's claim is that the whole machine, not just the filter cartridge, is sealed so air cannot bypass filtration — a design claim about the housing as much as the filter. Neither manufacturer publishes data that lets the two be ranked against each other directly.

Each one in full

Air purifiers

Xiaomi Smart Air Purifier 4 Compact

230 m (755 ft)³/h CADR · True HEPA · up to 27 m (89 ft)²

A compact HEPA purifier Xiaomi rates at 230 m (755 ft)³/h particulate CADR and 185 m (607 ft)³/h formaldehyde CADR for rooms up to 27 m (89 ft)². An OLED touchscreen shows live air quality, sleep mode is rated at 18.3 dB, and the app tracks a 6-12 month filter life.

Best for: A bedroom or small home office where a compact footprint and a low purchase price matter more than covering a large open-plan room.

7.0/10

≈ $120

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Air purifiers

Dyson Purifier Cool PC1

Sealed HEPA H13 · bladeless tower · fan + purifier

Dyson's Purifier Cool PC1 combines a bladeless tower fan with a fully sealed HEPA H13 filtration system the brand rates at 99.95% removal down to 0.1 micron, tested to EN 1822. Dyson does not publish a CADR figure or an absolute noise-level rating for this model.

Best for: A household that wants one device to handle both summer cooling and air purification and is willing to pay a premium for Dyson's sealed-filtration design and app ecosystem.

8.4/10

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Prices quoted in these summaries are dated readings. The live price is shown next to each product.