Pressure in a liquid increases steadily with depth because of the weight of the liquid above. In water it rises by about 1 atmosphere every 10 metres – which is why divers must equalise and why dams are thicker at the bottom.
How to use the Hydrostatic Pressure Calculator
- Liquid
- Liquid density
- Depth h
- Gravitational acceleration g
- Surface pressure p₀
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Choose the liquid, enter the depth, gravity and the surface pressure (usually atmospheric).
Inputs explained
| Field | What to enter |
|---|---|
| Liquid | Choose one: Fresh water (20 °C), Seawater, Air (sea level, 15 °C), Ethanol … |
| Liquid density | Units: kg/m³, g/cm³, g/mL, lb/ft³, lb/in³ |
| Depth h | Units: m, cm, mm, km, in, ft … |
| Gravitational acceleration g | Units: m/s², ft/s², g, cm/s² |
| Surface pressure p₀ | Units: kPa, Pa, bar, psi, atm, MPa |
Example values
How the main result changes when Liquid density changes and everything else stays at the example values above:
| Liquid density (kg/m³) | Absolute pressure (kPa) |
|---|---|
| 500 | 199.215 |
| 750 | 199.215 |
| 1,000 | 199.215 |
| 1,250 | 199.215 |
| 1,500 | 199.215 |
| 2,000 | 199.215 |
Formula
p = ρ·g·h + p₀
Worked example
Inputs — Liquid: Fresh water (20 °C); Depth h: 10 m; Gravitational acceleration g: 9.80665 m/s²; Surface pressure p₀: 101.325 kPa.
Results — Gauge pressure = 97.88998 kPa; Absolute pressure = 199.21498 kPa; In atmospheres (absolute) = 1.9661 atm.
Key terms
- Hydrostatic pressure
- Pressure due to the weight of a fluid at rest.
Frequently asked questions
How fast does water pressure rise?
About 9.8 kPa per metre – 1 atm every 10 m.
Does the container shape matter?
No – only the depth (the hydrostatic paradox).
What is gauge pressure?
Pressure above atmospheric.
Why are dams thicker at the base?
Water pressure is greatest at the bottom.