Attributes

Brand	-
Category	Robotics / STEM Teaching Tools / Sensors
Origin	-
Model Number	AHT21
Communication Interface	I2C
Operating Voltage	2.4V - 5.5V
Temperature Range	-40°C to +85°C
Humidity Range	0% to 100% RH
Temperature Accuracy	±0.3°C
Humidity Accuracy	±2% RH
Response Time	< 8 seconds
Package Type	DFN-8
Application	HVAC, Smart Home, Industrial Monitoring

6 reviews

Anonymous

Mar 17, 2026

Rating: 5/5

Fast shipping and works as described

Arrived well-packaged. Connected it immediately to my Raspberry Pi, and the library examples worked out of the box. The precision is impressive for this price point.

Anonymous

Mar 16, 2026

Rating: 5/5

Perfect for my weather station project

The AHT21 module works flawlessly with my Arduino setup. The I2C communication is stable, and the readings are consistent with my calibrated reference meter. Highly recommended for DIY enthusiasts.

Anonymous

Mar 15, 2026

Rating: 5/5

Reliable and compact

Small footprint makes it easy to fit into tight enclosures. The temperature and humidity readings sync quickly with my ESP32. Very satisfied with this purchase.

Anonymous

Mar 08, 2026

Rating: 4/5

Good accuracy, easy to integrate

Integrated this into a smart greenhouse controller. The humidity response is quite fast. Only giving 4 stars because the documentation could be slightly more detailed for beginners, but overall a solid sensor.

Anonymous

Mar 06, 2026

Rating: 4/5

Solid performance for the price

Been running three of these for a month now logging data every 10 minutes. No drift observed yet. The power consumption is also very low, which is great for battery-operated projects.

Anonymous

Mar 05, 2026

Rating: 5/5

Excellent anti-interference performance

Used this in an environment with some electrical noise, and the AHT21 held up perfectly. The data remains stable even when other motors are running nearby. Great build quality.

5 FAQ

Q: Can this sensor be used outdoors directly exposed to rain?

A: No, the AHT21 module is not waterproof. It should be housed in a breathable enclosure that protects it from direct water exposure while still allowing air circulation for accurate humidity readings.

Q: Is this module compatible with 3.3V logic systems like the ESP8266?

A: Yes, the AHT21 operates within a voltage range of 2.4V to 5.5V, making it fully compatible with both 3.3V and 5V logic systems including ESP8266 and ESP32.

Q: Does this come with a library for Arduino IDE?

A: While the module itself does not include a physical library disk, it is supported by several popular open-source libraries available in the Arduino Library Manager. Search for 'AHT21' or 'AHTxx' to find compatible code.

Q: What is the maximum cable length recommended for I2C communication with this sensor?

A: For reliable I2C communication, we recommend keeping the cable length under 20-30 cm without pull-up resistor adjustments. For longer distances, you may need to use an I2C extender or adjust pull-up resistors based on your specific setup.

Q: How often should the sensor be calibrated?

A: The AHT21 is factory-calibrated and typically maintains its accuracy over time under normal operating conditions. Recalibration is generally not required unless the sensor has been exposed to extreme conditions beyond its specified limits.

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