Adafruit SCD-40 - True CO2, Temperature and Humidity Sensor

The Adafruit SCD-40 is a photoacoustic true CO2 sensor that directly measures carbon dioxide concentration in ambient air, rather than estimating it from volatile organic compounds. It also includes integrated temperature and humidity sensing, providing comprehensive environmental data from a compact module.

Compared to the larger NDIR-based SCD-30, the SCD-40 uses a different measurement technique that allows a much smaller form factor while delivering similar data quality. Data is read over I2C with Arduino and CircuitPython libraries available for quick setup.

Key Features

• True CO2 Measurement – Photoacoustic sensing, not VOC-based estimation
• Measurement Range – 400 to 2,000 ppm CO2
• Accuracy – ±(50 ppm + 5% of reading)
• Integrated Temperature & Humidity – Built-in environmental sensors for compensation and standalone readings
• I2C Interface – STEMMA QT / Qwiic connectors for solderless hookup and daisy-chaining
• 3.3 V / 5 V Compatible – Onboard 3.3 V regulator provides clean, low-ripple power for accurate readings; level shifters for 5 V logic
• Compact Form Factor – Significantly smaller than NDIR-based CO2 sensors

Also Consider

• SCD-30 NDIR CO2 Sensor – Larger NDIR-based sensor with 400–10,000 ppm range and ±(30 ppm + 3%) accuracy

Ideal For

• Indoor air quality monitoring and ventilation studies
• Smart building and HVAC systems
• Classroom and office CO2 monitoring
• Environmental sensing and scientific experiments

Package Contents

• 1× Adafruit SCD-40 True CO2, Temperature & Humidity Sensor Breakout