What pressure is indicated by a gauge that measures pressures at or above atmospheric pressure?

A gauge that measures pressures at or above atmospheric pressure is designed to indicate gauge pressure. Gauge pressure refers to the pressure measured relative to atmospheric pressure; it reflects how much pressure exists above or below the atmospheric baseline.

In practical terms, if the gauge reads zero, it indicates that the measured pressure equals atmospheric pressure. As the pressure increases above atmospheric levels, the gauge pressure increases, providing a meaningful measurement for processes where atmospheric pressure is not a concern.

This is contrasted with other pressure types, such as absolute pressure, which considers the total pressure (including atmospheric pressure), and vacuum pressure, which measures pressures below atmospheric levels. Both of these terms relate to different contexts and reference points, making them unsuitable in this scenario where the gauge focuses solely on pressures at or above the atmospheric level.