Adafruit SCD-40 is a photoacoustic "true" CO₂ sensor that measures the carbon dioxide concentration in air directly in PPM units. Unlike VOC-based sensors, the SCD-40 does not estimate the value but measures it accurately, making it an excellent choice for air quality monitoring, scientific measurements, and ventilation studies.

The SCD-40 measures in the range 400–2000 ppm and offers an accuracy of ±(50 ppm + 5% of the reading). The sensor uses an I2C interface, and Arduino and CircuitPython/Python libraries are available. Its compact size makes it a smaller alternative to the SCD-30 model while maintaining high measurement accuracy.

The module is equipped with STEMMA QT connectors, which are compatible with the SparkFun Qwiic system. This allows the sensor to be connected easily without soldering or daisy-chained with other I2C devices. The board includes an integrated 3.3 V regulator and level shifter, so it can be used with both 3.3 V and 5 V logic.

Technical specifications

• Measurement range: 400–2000 ppm CO₂
• Accuracy: ±(50 ppm + 5% of the reading)
• Interface: I2C, STEMMA QT / Qwiic compatible
• Operating voltage: 3.3–5 V
• Integrated 3.3 V regulator and level shifter
• Compact design

Package includes

• 1 × Adafruit SCD-40 breakout (assembled and tested)
• Header pins

Links

• Product page