The combination between DS18B20 Waterproof temperature sensor and Arduino has been recently used as a data acquisition (DAQ) system on a temperature measurement for its user-friendly and relatively affordable price. Arduino can be a valid data acquisition device if the sensor is perfectly calibrated. This research proposed a calibration method for a temperature sensor DS18H20 Waterproof based on Arduino Uno using a thermometer calibrator ASTM 117C which value could be traced by a calibration medium of oil in an open surface bath. The election of oil as the medium is aimed to reduce its conditional instability so that the calibration could be done. There are 12 arranged DS18B20 waterproof sensors that will be calibrated alongside the ASTM 117C calibrator so that all the measurement points have the exact identical conditions. Such a system was done for having the small deviation characteristics between the oil temperature measured on the DS18B20 Waterproof sensor to the ASTM 117C mercury thermometer. The small deviation characteristics that presented as a linear equation is obtained by using a linear regression method. Calibration was done by using the ambient temperature as the energy to calibrate the sensors. The movement of ambient temperature will cause temperature slowly movement response on the medium (oil) and resulted a measurement points. DS18B20 waterproof sensors resulted a mean error of ± 3.00 % before calibration begun. Meanwhile after the calibration using the proposed method, the DS18B20 sensor has a smaller mean error of ± 0.85 %, so that obtained a more accurate sensor and it can be used for testing of Grashof Portable Incubator made by University of Indonesia.