Equation 3: Atmospheric Pressure

hHeight above the radius (m)
PhPressure at height (h), in standard atmospheres
PoPressure at radius (r), in Pascals (Pa)
e2.718281828... (natural logarithm)
MmMolar mass of the atmosphere (kg)
MpMass of the planet (kg)
TTemperature of the planet at the planetary radius (K)
rPlanetary radius (m)

Ph in Pascals (Pa) is obtained by using J=1
This is a simplified version of a very complex equation
This equation can also be used for depths (h < 0)

These calculations are available in a MS Excel format from here

Radius, Maximum and Mountain-top Atmospheric pressures

PlanetPoPmaxPminHeighest mountain
Earth110.3507Mount Everest
Venus91.17102.26844.7Mount Maxwell
Mars0.006910.008730.00085Mount Olympus

"90 Earth atmospheres" is often quoted as an excuse for the poor habitability of Venus. So it's important to note: atmospheric pressure on the surface of Venus starts at 44.7 atmospheres, at the top of Mount Maxwell.