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Head ↔ Pressure Calculator

Convert the height of a water column into the static pressure it produces — for sizing, fill heights and gravity systems.

Head ↔ Pressure

Convert vertical head of water to static pressure.

Head of water (m)

Pressure0.981 bar

Pressure981 mbar

Method: Level 2 plumbing science

How it works

Static pressure depends only on the vertical height of water above the point — not the pipe shape or the volume of water. Each metre of head adds about 0.098 bar (98 mbar), because pressure = density × gravity × height (1000 kg/m³ × 9.81 m/s² × 1 m ≈ 9810 Pa).

So pressure (bar) = head (m) × 0.0981, and head (m) = pressure (bar) ÷ 0.0981. As a rule of thumb, 1 bar ≈ 10.2 m of head.

Worked example

A cold-water storage cistern 10 m above an outlet gives 10 × 0.0981 ≈ 0.98 bar (about 981 mbar) of static pressure at that outlet.

Head and pressure questions

How many metres of head is 1 bar?

About 10.2 m of water head equals 1 bar of static pressure. Each metre of head adds roughly 0.098 bar, or 98 mbar.

Does pipe size or shape change static pressure?

No. Static pressure depends only on the vertical height of water above the point being considered — not on pipe diameter, route or the volume stored.

What head does a loft cistern give a shower?

Measure the vertical distance from the cistern water level down to the shower head. A 3 m height gives about 0.29 bar, which is why gravity showers often feel weak compared with mains-fed systems.