Nowadays, there are many sensors that can be directly connected to the microcontroller to measure and calculate the value of relative humidity immediately. However, the existing sensors are made designed and tested to measure the conditions of the location where the sensor is made, which will cause deviation of the results at other locations. Therefore, it should be known more accurately the characteristics of DHT22 sensor in the tropical region. This calibration is done by comparing the relative humidity value on the sensor with the relative humidity value obtained from the manual measurement by the ASTM E337-84 method that taken at the same time. The advantages of DHT22 sensor are relatively cheap and easily obtained through online purchases. The Data collected would be engineered to the output of the sensor so that the detected value on DAQ will generate humidity value that is close to the humidity value with the ASTM E337-84 method. In conclusion, DHT22 sensor has different characteristics than the existing specifications in the data sheet, and this calibration method can improve the performance of this DHT22 sensor that this sensor after calibration, DHT22 will be used fregmently for testing the performance of portable incubator made by Universitas Indonesia.