Regarding the survey results of 10 hospitals in Yogyakarta, the determination rate of oxygen medical use was still implemented in manual way using the multiplication flow rate of the oxygen (flow rate) per minute (3L/minute) with the length of time use. Based on the statement mentioned, the assessment could lead to the lack of transparency towards the oxygen gas volume used by the patients, so that it was able to harm them financially. Besides, the module making was expected to be able to identify the amount of oxygen gas volume use and the time of medical oxygen gas usage during the first installation until its completion use, so the oxygen gas utilization could be measured in a transparent and accurate volume. In addition, the calculation of the total volume and tariff charges in this module adopted the equation function formula y = 0.0148 (x) + 0.9704 obtained from the water flow sensor. Following this, the water flow sensor output was a box signal pulse in which it was calculated by the ATMega328 microcontroller to achieve the flow speed and volume. Therefore, the results of the measurement data were to compare the flow rate of 1 L / men - 6 L / men set on the oxygen regulator with the output value displayed on the LCD. Likewise, the percentage of error in this tool included 2.7%, so it was worth using because the error percentage value was below 10% and can display the burden of oxygen usage rates from the first time to finish use.