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Xiaomi Smart Air Purifier 4 and 4 Pro

Two Xiaomi purifiers that run locally in Home Assistant through the xiaomi_miio integration once you've extracted the device token. The 4 Pro moves more air; the 4 reports more sensors.

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The 2 side by side

Every column is read from the product's own notes page. Discontinued members sit last.

Xiaomi Smart Air Purifier 4 and 4 Pro compared: standout, setup, price band, price and where to buy.
Product	Standout	Setup	Price band	Price	Where to buy
Xiaomi Smart Air Purifier 4 4, PM2.5 + temperature and humidity sensors	Local Home Assistant control via Xiaomi Miio integration with built-in PM2.5, temperature, and humidity sensors.	moderate	mid	midband only	Check price at Xiaomi ↗
Xiaomi Smart Air Purifier 4 Pro 4 Pro, 500 m3/h CADR, OLED display	500 m3/h CADR covering up to 60 m2 with an OLED display, controllable fully locally over the miot protocol once the device token is extracted.	easy	mid	midband only	Check price at Xiaomi ↗

Which one to buy

The 4 Pro is the one for a medium to large room: 500 m3/h CADR covering up to 60 m2, an OLED display, and fan modes, PM2.5 and filter life all exposed locally.

The 4 is the one with temperature and humidity sensors alongside PM2.5 in Home Assistant, with a CADR that still covers medium to large rooms.

Both need a one-time Xiaomi cloud login to extract the token; the 4's replacement HEPA filters cost more than IKEA STARKVIND filters, and the 4 Pro is largely an import in the US.

I haven't run any of these; the picks are based on the spec sheets and what other Home Assistant users report.