Water Pressure Calculator

Convert feet of water to PSI, PSI to feet of head, or find how much pressure is left at an upstairs fixture.

What Do You Want to Find?
Vertical height of the water surface above the point you care about.
1 for water. Seawater about 1.025.
Fractions and decimals both work.
–
PSI
Pressure
Head
Bar
kPa
Meters of water
Household Range

Saved Readings

Items you add are saved in this browser.

NameHeight (Ft.)PSIBarRemove

How to Calculate Water Pressure from Height

Still water presses down with its own weight. A column of water 1 foot tall puts about 0.433 psi on the bottom, no matter how wide the column is, so it takes 2.31 feet of height to make 1 psi. That's why water towers are tall and why pressure drops on upper floors.

PSI = height (ft) × 0.433 × specific gravity
Height (ft) = PSI × 2.31 ÷ specific gravity
Pressure at a fixture = gauge pressure − 0.433 × height above the gauge

These are static pressures, with no water flowing. Running water loses more pressure to friction in the pipe, fittings and meter.

Worked Example

Head and Pressure

Feet of WaterPSIBarkPa

Household Pressure

Homes usually run at about 40 to 80 psi. The International Plumbing Code (604.8) requires a pressure-reducing valve where static pressure in the building exceeds 80 psi. Low pressure on an upper floor may need a booster pump.