Updated
Aranet

Aranet4 Home CO2 Monitor

The reference consumer CO2 monitor: a battery-powered e-ink puck with a true NDIR sensor that shows at a glance how badly a room needs ventilating.

4.5 / 5
Outstanding

Strengths

  • Genuine NDIR sensor with class-leading rated accuracy for a consumer device
  • Always-visible e-ink display with simple green/amber/red guidance - no app needed day to day
  • Runs for months to years on two AA batteries; rechargeables work

Watch outs

  • Premium price - notably more than newer rivals with comparable rated accuracy
  • Hardware has barely changed since release; no Wi-Fi, only short-range Bluetooth
  • Not waterproof and somewhat fragile - the e-ink screen wants a case in a bag
  • CO2 sensor True NDIR (Senseair Sunrise), 0-9999 ppm, accuracy +/-(30 ppm + 3% of reading)
  • Other sensors Temperature (0-50 C, +/-0.3 C), relative humidity, atmospheric pressure
  • Display Always-on e-ink with colour-coded CO2 status and optional buzzer (default red threshold 1400 ppm)
  • Power 2 x AA batteries; battery life from many months up to ~4 years depending on measurement interval and battery type

We may earn a commission if you buy through this link - it never changes the price you pay or our editorial verdict.

As an Amazon Associate I earn from qualifying purchases.

Portable CO2 monitor on a home office desk
By Rob Griffiths1 min read
CO2 sensor
True NDIR (Senseair Sunrise), 0-9999 ppm, accuracy +/-(30 ppm + 3% of reading)
Other sensors
Temperature (0-50 C, +/-0.3 C), relative humidity, atmospheric pressure
Display
Always-on e-ink with colour-coded CO2 status and optional buzzer (default red threshold 1400 ppm)
Power
2 x AA batteries; battery life from many months up to ~4 years depending on measurement interval and battery type
Connectivity
Bluetooth to the free Aranet Home app (trends, history, alert thresholds)
Dimensions
70 x 70 x 24 mm, 104 g
Calibration
Factory-calibrated; automatic background or manual recalibration supported
Warranty
2 years (extendable to 3)
Subscription
None