Water Pressure Calculator
Calculate static water pressure from a column height using P = ρ·g·h, in metric or imperial.
How it works
- 1Enter the vertical height (head) of the water column in metres or feet.
- 2The calculator applies P = ρ·g·h with water density 1000 kg/m³ and g = 9.80665 m/s².
- 3Results show kPa or psi, bar, psi, and Pa.
Use cases
- Sizing domestic plumbing and checking minimum pressure at fixtures.
- Verifying pipe pressure ratings for a rooftop-tank supply.
- Estimating pump discharge head for irrigation or fire systems.
Frequently asked questions
How much pressure does 1 metre of water give?
About 9.81 kPa (0.0981 bar or 1.42 psi) per metre. For 30 m of head: 30 × 9.81 ≈ 294 kPa ≈ 2.94 bar.
Why is my system pressure lower?
This is static (hydrostatic) pressure only. Flowing water loses pressure to friction in pipes and fittings, so dynamic pressure at a tap is always lower.
What is 0.433 psi per foot?
The imperial equivalent of ρ·g for water: 62.4 lb/ft³ ÷ 144 ≈ 0.433 psi per foot, so a 100 ft head gives about 43.3 psi.
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