It's summer and you're sweating and your hair's all frizzy and all you really want to know is why the weatherman said this morning that today's relative humidity would max out at a perfectly reasonable 52% when it feels more like 77%. Enter the HTU21D-F Temperature + Humidity Sensor - the best way to prove the weatherman wrong!

This I2C digital humidity sensor is an accurate and intelligent alternative to the much simpler Humidity and Temperature Sensor - SHT15 Breakout It has a typical accuracy of ±2% with an operating range that's optimized from 5% to 95% RH. Operation outside this range is still possible - just the accuracy might drop a bit. The temperature output has an accuracy of ±1°C from -30~90°C. If you're looking to measure temperature more accurately, we recommend the MCP9808 High Accuracy I2C Temperature Sensor Breakout Board.
Such a lovely chip - so we spun up a breakout board that includes the Filtered version (the white bit of plastic which is a PTFE filter to keep the sensor clean), a 3.3V regulator and I2C level shifting circuitry. This lets you use it safely with any kind of microcontroller with 3.3V-5V power or logic.
To get you going fast, we spun up a custom made PCB in the STEMMA QT form factor, making them easy to interface with. The STEMMA QT connectors on either side are compatible with the SparkFun Qwiic I2C connectors. This allows you to make solderless connections between your development board and the HTU21Ds or to chain them with a wide range of other sensors and accessories using a compatible cable. QT Cable is not included, but we have a variety in the shop.
Each order comes with one fully assembled and tested PCB breakout and a small piece of header. You'll need to solder the header onto the PCB to use in a breadboard but it's fairly easy and takes only a few minutes even for a beginner.

It's also very easy to use, thanks to our Arduino library and tutorial. Check out our tutorial for pinouts, wiring, files, etc.

Technical Details:

I2C 7-bit address 0x40
PCB CAD files, datasheets, Fritzing object, etc available in the tutorial

Revision History:

As of November 2022 - we've updated this PCB with Adafruit Pinguin to make a lovely and legible silkscreen - you may get the new PCB or the older version with vector fonts - both are identical other than the fancy silkscreen. Additionally, this sensor breakout may come with black or tan STEMMA QT connectors. They work the same!
As of March 23, 2021 - we've updated this sensor to be STEMMA QT compatible - that means there's now an easy way to plug-and-play this sensor without any soldering! The physical shape has changed a little, and the pinout has changed to our QT standard ordering.
Product Dimensions: 25.5mm x 17.0mm x 5.0mm / 1.0" x 0.7" x 0.2"

Package Includes: