What is hydrostatic pressure?

Hydrostatic pressure is the pressure at a point within a stationary fluid caused by the weight of the fluid above that point. It increases linearly with depth according to P = ρgh.

Does this include atmospheric pressure?

No. This calculator gives gauge pressure — the pressure due to the fluid alone, not including the atmospheric pressure acting on the surface. To get absolute pressure, add 101,325 Pa (1 atm) to the Pa result.

What is the density of seawater?

Seawater density is approximately 1025 kg/m³ at surface salinity (~35 g/kg) and 20 °C. It varies slightly with temperature and salinity; the value used here is a standard average.

Why does the shape of the container not matter?

Hydrostatic pressure depends only on vertical depth, fluid density, and gravity — not on the horizontal dimensions or shape of the container. This is known as the hydrostatic paradox.

Can I use this for gases?

For small height differences, yes — treat the gas density as constant. For large columns (e.g. atmospheric pressure over hundreds of metres), density varies significantly with altitude and the simple P = ρgh formula is an approximation only.

Hydrostatic Pressure Calculator

Name: Hydrostatic Pressure Calculator
Availability: InStock
Author: Nham Vu

Calculate fluid pressure at any depth using P = ρgh, with results in Pa, kPa, bar, and psi.

Inputs

Fluid

Depth

Gravitational acceleration

Results

Enter depth and click Calculate

Summary

Calculate fluid pressure at any depth using P = ρgh, with results in Pa, kPa, bar, and psi.

How it works

Select a fluid from the preset list or choose "Custom" to enter any density.
Enter the depth (how far below the surface the point is).
Choose the depth unit: metres or feet.
The calculator applies P = ρgh and displays the gauge pressure.
Results appear simultaneously in Pa, kPa, bar, and psi.

Use cases

Determine water pressure at the bottom of a tank or dam.
Calculate pressure on a submarine hull at a given ocean depth.
Size pumps and valves based on the static head in a piping system.
Verify structural loads on underwater foundations or retaining walls.
Estimate mercury pressure in a manometer column.
Check diving pressure limits for scuba or saturation diving.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu