PJRC
PJRC CO2 Gadget DIY Kit
$45
PJRC CO2 Gadget DIY Kit Overview
The PJRC CO2 Gadget DIY Kit is a budget 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 400-5000 ppm measurement range. At $45, it is aimed at DIY projects, budget-conscious buyers and on-the-go monitoring.
In day-to-day use, the CO2 Gadget DIY Kit offers an onboard display, so you can read levels at a glance without opening an app, plus WiFi and USB connectivity for logging trends and setting alerts, plus a portable design with USB powered / battery optional of battery life, making it practical to carry between rooms or when travelling.
Best For
Full Specifications
| Price | $45 |
| Sensors | CO2, Temperature, Humidity |
| Sensor Type | NDIR |
| Connectivity | WiFi, USB |
| Display | Yes |
| Portable | Yes |
| Battery Life | USB powered / battery optional |
| CO2 Accuracy | ±50 ppm |
| CO2 Range | 400-5000 ppm |
Pros & Cons
Pros
- ✓True NDIR CO2 sensor (not an eCO2 estimate)
- ✓Built-in display for at-a-glance readings
- ✓WiFi connectivity for remote monitoring and history
- ✓Accessible price point for a real CO2 sensor
Cons
Compare this monitor with others using our Monitor Comparison Tool
Frequently Asked Questions
Is the PJRC CO2 Gadget DIY Kit accurate?+
The PJRC CO2 Gadget DIY Kit uses a NDIR sensor with a stated accuracy of ±50 ppm over a range of 400-5000 ppm. NDIR is the proven reference technology for consumer CO2 monitoring.
What does the PJRC CO2 Gadget DIY 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 PJRC CO2 Gadget DIY Kit need WiFi?+
The PJRC CO2 Gadget DIY Kit supports WiFi (plus USB) for remote monitoring, but the onboard display works without any connection.
Is the PJRC CO2 Gadget DIY Kit worth it in 2026?+
At $45, the PJRC CO2 Gadget DIY Kit is a solid choice for DIY projects, budget-conscious buyers 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 PJRC CO2 Gadget DIY Kit battery last?+
The PJRC CO2 Gadget DIY Kit runs for USB powered / battery optional, and its portable design makes it easy to move between rooms or take when travelling.