Testo
Testo 440 CO2 Kit
$900
Testo 440 CO2 Kit Overview
The Testo 440 CO2 Kit is a professional-grade CO2 monitor that tracks CO2, Temperature and Humidity. It uses a NDIR sensor — the technology we recommend for reliable CO2 readings — with a stated accuracy of ±50 ppm across a 0-10000 ppm measurement range. At $900, it is aimed at professional applications and HVAC integration.
In day-to-day use, the 440 CO2 Kit offers an onboard display, so you can read levels at a glance without opening an app, plus Bluetooth connectivity for logging trends and setting alerts, plus a portable design with 10 hours of battery life, making it practical to carry between rooms or when travelling.
Best For
Full Specifications
| Price | $900 |
| Sensors | CO2, Temperature, Humidity |
| Sensor Type | NDIR |
| Connectivity | Bluetooth |
| Display | Yes |
| Portable | Yes |
| Battery Life | 10 hours |
| CO2 Accuracy | ±50 ppm |
| CO2 Range | 0-10000 ppm |
Pros & Cons
Pros
- ✓True NDIR CO2 sensor (not an eCO2 estimate)
- ✓Built-in display for at-a-glance readings
Cons
- ✗Bluetooth only — no remote access when you are away from home
- ✗Premium price compared with entry-level alternatives
Compare this monitor with others using our Monitor Comparison Tool
Frequently Asked Questions
Is the Testo 440 CO2 Kit accurate?+
The Testo 440 CO2 Kit uses a NDIR sensor with a stated accuracy of ±50 ppm over a range of 0-10000 ppm. NDIR is the proven reference technology for consumer CO2 monitoring.
What does the Testo 440 CO2 Kit measure?+
It measures CO2, Temperature, Humidity. CO2 is the key metric for judging ventilation — levels below 800 ppm indicate well-ventilated air.
Does the Testo 440 CO2 Kit need WiFi?+
No. The Testo 440 CO2 Kit uses Bluetooth for syncing with the app and shows readings on its built-in display.
Is the Testo 440 CO2 Kit worth it in 2026?+
At $900, the Testo 440 CO2 Kit is a solid choice for professional applications and HVAC integration. Its NDIR sensor puts it ahead of cheaper eCO2 estimators. Compare alternatives in our monitor comparison tool before buying.
How long does the Testo 440 CO2 Kit battery last?+
The Testo 440 CO2 Kit runs for 10 hours, and its portable design makes it easy to move between rooms or take when travelling.