Abstract: The invention relates to an electronic gauge (I) for use with a compressed gas cylinder (2). The electronic gauge (I) comprises a display interface (4), a pressure sensor (5) having a pressure sensing element (6) and an amplification circuit (7) for amplifying a signal from the pressure sensing element (6), a temperature sensor (8), and a control electronics board (I 0) connected to the display interface (4), the pressure sensing element (6) and the temperature sensor (8). The invention also relates to a method of calculating time remaining until substantially all gas in a compressed gas cylinder (2) has been depleted, and a method of monitoring that a residual pressure valve of a gas cylinder (2) is operational.