Adafruit HTS221 Temp & Humidity Sensor Breakout Board

Adafruit HTS221 Temperature and Humidity Sensor Breakout Board is designed around the ST HTS221, a capacitive digital humidity and a temperature sensor. The device allows the user to take measurements of the relative humidity. The HTS221 can measure relative humidity from 0%-100% RH with a sensitivity of 0.004% and 3.5%, and accuracy between 20 to 80%. It can also measure temperature from -40°C to 120°C, with a resolution of 0.016°C with ±0.5°C accuracy between +15°C and +40°C.

The HTS221 is an inexpensive humidity sensor which makes it great for everyday measurement applications. The device lets the user choose between a 3-wire SPI or the ever-popular I2C, which only needs two wires for data. If the user decides to use I2C, the SparkFun Qwiic compatible STEMMA QT connectors are included so there is no need to solder. Since the HTS221 is a super small 2mm square, it has been put in a breakout board with level shifting and a power regulator. This makes it easy to use on a breadboard with either a 5V logic level device like a Metro 328 or Arduino Uno, or with 3.3V logic level devices like a Feather M4 or Raspberry Pi of the user's choice.

Adafruit has created libraries for Arduino and CircuitPython or Python. These libraries also include written example code and instructions. These allow the user to determine the approximate relative humidity level and temperature in only a few minutes.


  • Capacitive digital sensor for relative humidity and temperature
  • 0 to 100% relative humidity range
  • 3 to 5 VDC power and logic
  • Selectable ODR from 1Hz to 12.5Hz
  • 0.004% RH/LSB high rH sensitivity
  • ±3.5% RH, 20 to 80% RH humidity accuracy
  • ± 0.5°C, +15°C to +40°C temperature accuracy
  • Embedded 16-bit ADC with 16-bit humidity and temperature output data
  • SPI and I2C interfaces, with an I2C address of 0x5F
  • ST factory calibrated
Published: 2020-03-31 | Updated: 2022-03-10