A fully automated hydrometer calibration system at the Egyptian National Institute of Standards (NIS) has been established and realized to be used in measuring the density of the liquids and calibration of the hydrometers in the applicable range from 0.5 g/cm3 up to 2 g/cm3. The hydrostatic weighing technique based on Cuckow's method was used in the calibration using the hydrometer calibration system. The density of the distilled water was used as a reference liquid (Density= 998.2 kg/m3 at 20 ºC). A comparison between the results obtained from the French National Metrology Institute (LNE) system and the Egyptian National Institute of Standards (NIS) system was performed. The En-Value analytical technique based on calculating the reference value between the two institute's results and associated uncertainties was used. All the results of the Egyptian National Institute of Standards (NIS) system are satisfactory compared to the reference value of the measurements. An expanded uncertainty about 5.5×10-5 g/cm3 at confidence level of 95% and (K=2) was achieved using the NIS Hydrometer Calibration System.