Extech
Extech CO240
$280
Extech CO240 Overview
The Extech CO240 is a premium 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 $280, it is aimed at professional applications and offices.
In day-to-day use, the CO240 offers an onboard display, so you can read levels at a glance without opening an app, plus a stationary design (USB powered) best suited to continuous monitoring in a fixed location.
Best For
Full Specifications
| Price | $280 |
| Sensors | CO2, Temperature, Humidity |
| Sensor Type | NDIR |
| Connectivity | |
| Display | Yes |
| Portable | No |
| Battery Life | USB powered |
| 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
- ✗Not designed for portable use
- ✗Premium price compared with entry-level alternatives
Compare this monitor with others using our Monitor Comparison Tool
Frequently Asked Questions
Is the Extech CO240 accurate?+
The Extech CO240 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 CO240 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 CO240 need WiFi?+
No. The Extech CO240 works standalone and shows readings on its built-in display.
Is the Extech CO240 worth it in 2026?+
At $280, the Extech CO240 is a solid choice for professional applications and offices. Its NDIR sensor puts it ahead of cheaper eCO2 estimators. Compare alternatives in our monitor comparison tool before buying.