Pressure is another important aspect of fluid mechanics, and is one of the elements normally calculated in a fluids problem. Pressure can be expressed in two different ways. It can be expressed as gage pressure, and absolute pressure. Gage pressure is a pressure measurement that doesn’t take in consideration of atmospheric pressure, while absolute pressure includes atmospheric pressure. Refer to equation 1.

**(Eq 1) ** $P_{abs}=P_{gage}+P_{atm}$

Atmospheric pressure at sea level is 101 kpa in SI units and 14.7psi in English units.