Pressure and fluid head

Pump head and gauge pressure are the same thing in different units. Pressure = density × gravity × head.

Formulas

head (ft) = psi × 2.31 / SG
psi = head (ft) × SG / 2.31
head (m) = bar × 10.197 / SG

Water at about 4 °C (999.97 kg/m³) is the reference. The 2.31 ft per psi figure is for water near room temperature; fuels and oils have specific gravity below 1 and need more height for the same pressure.

Worked example

A pump that produces 100 psi on water has a head of 100 × 2.31 = 231 ft (70.4 m); the calculator, using exact water density, gives 230.7 ft. On a fluid with SG 0.85, the same 100 psi is 271.8 ft of head.

psi to bar · Pressure converter · ft to m