# Aranet4 Home Wireless Indoor Air Quality Sensor, NDIR CO2 Monitor

Source: https://www.ranked10.co.uk/home/best-air-quality-monitor/aranet4-home-ndir-co2
Ranked #1 in "Best Air Quality Monitor 2026: Fewer Numbers, Better Sensors": https://www.ranked10.co.uk/home/best-air-quality-monitor

- Price: £189.00 (checked on Amazon UK on 2026-09-11)
- Amazon rating: 4.6 from 1,813 ratings
- Buy on Amazon: https://www.amazon.co.uk/dp/B07YY7BH2W?tag=ranked10-21

The Aranet4 Home is the best-rated monitor in this ranking: 4.6 stars from 1,813 ratings, with 84 per cent five-star and only 4 per cent one-star. It measures CO2 with an NDIR sensor, plus temperature, humidity and air pressure, on an e-ink display powered by two AA batteries.

It takes first place because it does less and measures it properly. Four published measurements against the fifteen a cheap listing will claim, an included battery life measured in months rather than hours, and no account or subscription. What it does not do is particles: there is no PM2.5 reading here, which is the one gap to know about before buying.

## Specification

| Field | Value |
|---|---|
| What it measures | CO2, temperature, humidity, pressure |
| CO2 sensor | NDIR |
| Ratings | 4.6 from 1,813 |
| Power | 2 AA batteries, months of life |
| Connectivity | Bluetooth app, no WiFi |
| Price | £189.00 |

## Questions people ask

**Why does the most expensive monitor measure the fewest things?**

Because it uses a real NDIR CO2 sensor instead of estimating everything from one cheap VOC chip. Named sensors cost money; a long feature list costs nothing.

**Does it measure PM2.5?**

No. It measures CO2, temperature, humidity and pressure. For particles you need a laser particle counter, which the Temtop monitors below have.

**Do I need WiFi?**

No. Readings go to the app over Bluetooth and stay on your phone, with no account or subscription.

**How long do the batteries last?**

Two AA cells and an e-ink display, which the listing describes as an energy-efficient pairing with months of life. Batteries are included.

**Is CO2 worth monitoring on its own?**

It is the number that tells you when to ventilate, and that is exactly how buyers describe using it — knowing when to open a window.

**How many ratings does it have?**

1813 at the time of collection, averaging 4.6 stars, with 84 per cent five-star and 4 per cent one-star.