Water Pressure Calculator
Height Alone Determines Static Pressure
A column of standing water exerts pressure at its base purely because of its own weight and height — not its volume, container shape, or diameter. This is why a water tower a hundred feet up can pressurize an entire municipal system, and why the elevation difference between a rooftop tank and a ground-floor fixture matters as much as any pump. This calculator converts between vertical height and the static pressure it produces, in either direction.
The Formula
Height (ft) = Pressure (psi) ÷ 0.433
The constant 0.433 psi per foot comes directly from water's density: a column of water one foot tall and one square inch in cross-section weighs 0.433 lb, which is the pressure at its base under standard gravity.
Where This Calculation Matters
- Gravity-fed systems — calculating how much pressure a tank at a given elevation will deliver to fixtures below it.
- Multi-story buildings — estimating the pressure loss or gain fixtures experience relative to a building's water entry point based on floor height.
- Well and pump systems — converting a required delivery pressure into the elevation head a pump needs to overcome.
- Irrigation from elevated sources — determining available pressure at a field or garden fed by a hillside tank or reservoir.
Static Pressure by Height
| Height | Static pressure |
|---|---|
| 10 ft | 4.33 psi |
| 20 ft | 8.66 psi |
| 30 ft | 12.99 psi |
| 40 ft | 17.32 psi |
| 50 ft | 21.65 psi |
| 100 ft | 43.3 psi |
Most residential fixtures are rated for 40–80 psi; a 100 ft elevated source alone would need pressure regulation before it reaches typical plumbing.
How to Use This Calculator
- Choose a direction: Height → Pressure or Pressure → Height.
- In Height mode, enter the water column height in feet.
- In Pressure mode, enter the pressure in psi.
- Select Calculate to get the converted value.
Related Calculations
This is static pressure only — for the additional pressure lost to friction as water actually flows through pipe, see the Pipe Pressure Drop Calculator. To size a heater for the resulting supply, use the Water Heater Size Calculator.