Extech
Extech CO250
$350
Extech CO250 Overview
The Extech CO250 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 0-5000 ppm measurement range. At $350, it is aimed at professional applications and on-the-go monitoring.
In day-to-day use, the CO250 offers an onboard display, so you can read levels at a glance without opening an app, plus USB connectivity for logging trends and setting alerts, plus a portable design with 24 hours (6x AA) of battery life, making it practical to carry between rooms or when travelling.
Best For
Full Specifications
| Price | $350 |
| Sensors | CO2, Temperature, Humidity |
| Sensor Type | NDIR |
| Connectivity | USB |
| Display | Yes |
| Portable | Yes |
| Battery Life | 24 hours (6x AA) |
| CO2 Accuracy | ±50 ppm |
| CO2 Range | 0-5000 ppm |
Pros & Cons
Pros
- ✓True NDIR CO2 sensor (not an eCO2 estimate)
- ✓Built-in display for at-a-glance readings
Cons
- ✗No wireless connectivity for logging or alerts
- ✗Premium price compared with entry-level alternatives
Compare this monitor with others using our Monitor Comparison Tool
Frequently Asked Questions
Is the Extech CO250 accurate?+
The Extech CO250 uses a NDIR sensor with a stated accuracy of ±50 ppm over a range of 0-5000 ppm. NDIR is the proven reference technology for consumer CO2 monitoring.
What does the Extech CO250 measure?+
It measures CO2, Temperature, Humidity. CO2 is the key metric for judging ventilation — levels below 800 ppm indicate well-ventilated air.
Does the Extech CO250 need WiFi?+
No. The Extech CO250 works standalone and shows readings on its built-in display.
Is the Extech CO250 worth it in 2026?+
At $350, the Extech CO250 is a solid choice for professional applications and on-the-go monitoring. Its NDIR sensor puts it ahead of cheaper eCO2 estimators. Compare alternatives in our monitor comparison tool before buying.
How long does the Extech CO250 battery last?+
The Extech CO250 runs for 24 hours (6x AA), and its portable design makes it easy to move between rooms or take when travelling.