Ecowitt
Ecowitt WH45
$70
Ecowitt WH45 Overview
The Ecowitt WH45 is a budget CO2 monitor that tracks CO2, PM2.5, PM10, Temperature and Humidity. It uses a NDIR sensor — the technology we recommend for reliable CO2 readings — with a stated accuracy of ±75 ppm across a 400-5000 ppm measurement range. At $70, it is aimed at home use, budget-conscious buyers and smart home setups.
In day-to-day use, the WH45 offers no built-in display — readings are accessed through a connected app or dashboard, plus RF 915MHz connectivity for logging trends and setting alerts, plus a stationary design (USB powered) best suited to continuous monitoring in a fixed location.
Best For
Full Specifications
| Price | $70 |
| Sensors | CO2, PM2.5, PM10, Temperature, Humidity |
| Sensor Type | NDIR |
| Connectivity | RF 915MHz |
| Display | No |
| Portable | No |
| Battery Life | USB powered |
| CO2 Accuracy | ±75 ppm |
| CO2 Range | 400-5000 ppm |
Pros & Cons
Pros
- ✓True NDIR CO2 sensor (not an eCO2 estimate)
- ✓Multi-parameter monitoring: CO2, PM2.5, PM10, Temperature, Humidity
- ✓Accessible price point for a real CO2 sensor
Cons
- ✗No onboard display — requires the app to check readings
- ✗No wireless connectivity for logging or alerts
- ✗Not designed for portable use
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Frequently Asked Questions
Is the Ecowitt WH45 accurate?+
The Ecowitt WH45 uses a NDIR sensor with a stated accuracy of ±75 ppm over a range of 400-5000 ppm. NDIR is the proven reference technology for consumer CO2 monitoring.
What does the Ecowitt WH45 measure?+
It measures CO2, PM2.5, PM10, Temperature, Humidity. CO2 is the key metric for judging ventilation — levels below 800 ppm indicate well-ventilated air.
Does the Ecowitt WH45 need WiFi?+
No. The Ecowitt WH45 works standalone.
Is the Ecowitt WH45 worth it in 2026?+
At $70, the Ecowitt WH45 is a solid choice for home use, budget-conscious buyers and smart home setups. Its NDIR sensor puts it ahead of cheaper eCO2 estimators. Compare alternatives in our monitor comparison tool before buying.