**Units in pressure calculator**

atm=atmosphere, C=Celsius, cm=centimeter, F=Fahrenheit, ft=foot, g=gram, in=inch, kg=kilogram,
km=kilometer, lb=pound, m=meter, mbar=millibar, mm=millimeter, M=Mega, N=Newton, Pa=Pascal

**Pressure equation:** P = ρgh

where P = pressure (N/m^{2}), ρ = mass density of fluid (kg/m^{3}),
g = acceleration due to gravity = 9.8066 m/s^{2}, h = height of fluid column (m)

(SI units shown in equation, but calculation converts a variety of units)

**Introduction**

Engineers and others often need a conversion between pressure and height of fluid column.
For instance, if a swimming pool is 4 m deep, the pressure at the bottom can be
computed. Or, if a fire hydrant must operate at a static pressure of 40 psi, the
water column equivalent to 40 psi can be computed. Pressures can also be computed in
terms of gas columns, so we have included some built-in values for gas density.

Density must be entered as a positive number. Height and pressure can be entered as negative numbers. The calculator does not check for unrealistic heights or pressures, such as pressure below that of a complete vacuum.

**References**

All fluid mechanics textbooks discuss static pressure. A sampling of references
follows.

Mays, L. W. editor. 1999. Hydraulic design handbook. McGraw-Hill Book Co.

Munson, B.R., D. F. Young, and T. H. Okiishi. 1998. Fundamentals of Fluid Mechanics. John Wiley and Sons, Inc. 3ed.

Streeter, V. L., E. B. Wylie, and K. W. Bedford. 1998. Fluid Mechanics. WCB/McGraw-Hill. 9ed.

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