The invention relates to a density monitor (10) for monitoring a gas density in a gas chamber (20). The density monitor (10) comprises a measuring apparatus (12) having a first measuring device (24) and a second measuring device (28), the two measuring devices (24; 28) being coupled together. The first measuring device (24) is designed to measure a first pressure range (62) in relative terms with respect to an atmosphere, and the second measuring device (28) is configured to measure a second pressure range (64) in absolute terms. The density monitor (10) further comprises an indicator device (50), which is designed to indicate the two pressure ranges (24; 28). The density monitor (10) also comprises a movable drive element (48), which is designed to drive the indicator device (50), wherein at least one of the two measuring devices (24; 28) is designed to move the drive element (48) in order to drive the indicator device (50), wherein the indicator device (50) comprises an indicator element (58) which is designed to indicate the two pressure ranges (62, 64).