Xiaomi has introduced the Mijia Smart Humidity and Temperature Meter 3 Pro, a new indoor monitoring device that expands beyond basic temperature and humidity tracking by adding carbon dioxide (CO₂) detection.
The device is now listed through Xiaomi’s retail channels, with crowdfunding scheduled to begin on September 21 at 10:00 AM, positioning it as a compact smart home monitoring device for everyday indoor use. Its regular suggested retail price is 149 yuan, while early crowdfunding backers can purchase it for 114 yuan.
CO₂ Monitoring Is the Major Upgrade
The biggest change compared with the previous generation is the addition of real-time CO₂ concentration monitoring.
Xiaomi says the new meter uses a next-generation low-power thermal-conductivity CO₂ sensor from Sensirion. It can continuously measure indoor carbon dioxide levels and communicate the current air-quality status through a three-color indicator.
This gives the device a more practical role in everyday indoor monitoring. Instead of simply showing whether a room is hot, cold, dry or humid, it can also help users notice when ventilation may need attention.
Larger 3.6-Inch Display Shows More Information
The Mi Home Smart Humidity and Temperature Meter 3 Pro features a 3.6-inch LCD display, along with a slimmer-bezel design compared with the previous model.
The screen can show several types of information, including:
- CO₂ concentration
- Temperature
- Humidity
- Date
- Day of the week
- Time
Users can switch between different display layouts with a single action, allowing the screen to be configured around the information they want to see most often.
Works With Xiaomi’s Smart Home Ecosystem
The new meter is also designed to work as part of a connected smart home rather than operating as an isolated sensor.
It supports Xiaomi mijia smart-home integration and can connect with other compatible devices through a Bluetooth Mesh gateway. Temperature, humidity and CO₂ readings can be used as triggers for automated actions.
For example, users can configure a CO₂ threshold in the Mi Home App. When the measured level reaches the configured limit, a compatible smart speaker can automatically issue a voice reminder.
This makes the sensor more useful in rooms where users want automatic notifications instead of having to check the display manually.
Historical Data Can Be Viewed in the App
After pairing the meter with the Mi Home App and a compatible Bluetooth Mesh gateway, measurement data can be synchronized to the cloud.
The app can then generate historical curves showing changes in temperature and humidity, as well as CO₂ concentration, making it easier to track indoor environmental trends over time. This allows users to look beyond a single reading and identify longer-term changes in indoor conditions.
For example, a user could compare CO₂ levels at different times of day or observe how ventilation affects the readings over several days.
Flexible Placement and Long Battery Life
The Mi Home Smart Humidity and Temperature Meter 3 Pro supports both desktop placement and magnetic mounting, giving users more flexibility when deciding where to install it.
Despite the larger display and additional sensing capability, Xiaomi has retained a low-power design. The device uses a single CR2450 coin-cell battery and is rated for approximately one year of battery life.
A More Capable Indoor Environment Monitor
The new model is essentially an expansion of the traditional temperature-and-humidity meter concept. Its most important addition is not the larger display, but the ability to monitor CO₂ alongside temperature and humidity.
At 114 yuan during crowdfunding, the Mi Home Smart Humidity and Temperature Meter 3 Pro combines environmental monitoring, historical data tracking and smart-home automation in a compact device. Whether that extra functionality is useful will largely depend on whether users want CO₂ data and automated ventilation-related reminders in their homes.