Aranet4 Home Wireless Indoor CO2 & Air Quality Monitor review
Knowing, from the other side of the room and without touching your phone, when to open a window.
By Tom Calder · Price last checked 20 Sep 2026, 12:29 BST · price-tracked
The best CO2 instrument in this cluster by a clear margin, with a manufacturer-stated NDIR accuracy of ±(30 ppm + 3% of reading) and a display you can genuinely read across a room. It does one job properly and makes no pretence otherwise: no particulates, no VOCs, no radon and — this is the point readers most often get wrong — no carbon monoxide whatsoever. Bluetooth only, so there is no checking in on it while you are out.
as of 20 Sep 2026, 12:29 BST · Details
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- Manufacturer-stated CO2 accuracy of ±(30 ppm + 3% of reading) from an NDIR sensor
- Large-digit e-ink display with traffic-light status, readable from across a room
- 2x AA lasts years — up to around four on alkalines, up to seven on lithium cells
- CO2, temperature, humidity and pressure only — no PM2.5, VOC, radon or carbon monoxide
- Bluetooth only with no Wi-Fi, so no remote checking or alerts when you are out of range
- That accuracy figure is a manufacturer specification, not an independently certified one
Who shouldn't buy this
you want particulates or radon as well — the Airthings View Plus covers all three at a broadly similar price.
Key specs
| Measures | CO2 (NDIR), temp, humidity, pressure. No PM2.5, VOC, radon or CO. |
| Display | Large-digit e-ink, readable across a room, traffic-light status |
| Connectivity | Bluetooth only — no Wi-Fi; Aranet Home app for history/export |
| Power | 2x AA — up to ~4 years alkaline, up to 7 years on lithium |
Our rating is a considered spec-and-evidence verdict: we verify every specification against at least two independent sources, re-check the UK price on a schedule where we can track it automatically, and say plainly who a product isn't for. Commissions never change a rating. Read the full methodology →
Alternatives to consider
as of 20 Sep 2026, 12:29 BST · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.as of 20 Sep 2026, 12:29 BST · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.as of 20 Sep 2026, 12:29 BST · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.Want this cheaper?
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