Calibration Guide

Calibrating your UltimateSensor Mini v1 helps keep CO2, temperature and humidity readings accurate.

CO2 Calibration

The Mini v1 uses the Sensirion SCD41 for CO2 measurement. CO2 readings can need up to 24 hours to stabilize after first boot.

For manual calibration:

1. Place the Mini v1 outdoors or near fresh outdoor air, protected from rain.
2. Leave it powered for at least 10 minutes.
3. Open the Mini v1 device in Home Assistant.
4. Press the CO2 Manual Calibration button.
5. Wait for the device to apply the calibration.

Temperature and Humidity

Temperature and humidity can be influenced by placement. Avoid:

• Direct sunlight
• Radiators
• Electronics that emit heat
• Ventilation outlets
• Closed cabinets with poor airflow

To correct a reading, change Temperature Offset (default 2.3) or Humidity Offset (default -1) on the device page in Home Assistant. The values stay saved after a restart.

Voice Assistant Placement

If you use voice assistant, avoid placing the Mini v1 directly next to TVs, speakers, fans or other constant noise sources.