Gauge pressure - (College Physics I – Introduction) - Vocab, Definition, Explanations | Fiveable

Definition

Gauge pressure is the pressure relative to atmospheric pressure. It is the difference between absolute pressure and atmospheric pressure.

Gauge pressure can be positive or negative, depending on whether the measured pressure is above or below atmospheric pressure.
The equation for gauge pressure is $P_{gauge} = P_{absolute} - P_{atm}$.
In fluid statics, gauge pressures are commonly used because they simplify calculations by subtracting out atmospheric pressure.
A tire gauge measures the gauge pressure of the air inside a tire, not the absolute pressure.
In many practical applications, such as measuring blood pressure or water depth, gauge pressure is more relevant than absolute pressure.

The total pressure exerted on a system, including atmospheric and any additional applied pressures.

The weight of the Earth's atmosphere pressing down on everything at sea level, approximately equal to 101.3 kPa.

Pressure Measurement: $$\text\{Techniques and devices used to measure forces exerted by gases or liquids per unit area.\}$$