What formula does this calculator use?

It uses the hydrostatic pressure formula P = ρgh, where ρ is fluid density (kg/m³ or lb/ft³), g is gravitational acceleration (m/s² or ft/s²), and h is depth (m or ft). The result is gauge pressure; add atmospheric pressure (101,325 Pa or 14.696 PSI) for absolute pressure.

What is the pressure at 10 meters underwater?

Fresh water (ρ = 1000 kg/m³) at 10 m depth gives gauge pressure ≈ 98,100 Pa (98.1 kPa, ~0.968 atm, ~14.23 PSI). Add one atmosphere for absolute pressure: ~196,425 Pa (~1.968 atm, ~28.5 PSI).

Why does pressure increase with depth?

Deeper fluid has more fluid above it pushing down. Each additional meter of water adds the weight of that fluid column to the pressure below — hence pressure grows linearly with depth.

Can I use this for gases?

The formula P = ρgh assumes incompressible fluid (constant density). It is accurate for liquids. Gases are compressible and require more complex equations (e.g., barometric formula) for precise results.

What is the difference between gauge and absolute pressure?

Gauge pressure is measured relative to atmospheric pressure (it is zero at the surface). Absolute pressure includes atmospheric pressure on top. Enable "Add atmospheric pressure" to see absolute values.

What density should I use for seawater?

Average seawater density is about 1025 kg/m³ (64.0 lb/ft³). This varies with salinity and temperature; the preset uses 1025 kg/m³ as a standard value.

Fluid Pressure Calculator

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

Compute fluid pressure at a given depth using density, gravity, and depth — with metric and imperial unit support.

Fluid Pressure Inputs

Unit System

Fluid Preset

Fluid Density (kg/m³)

Depth / Height (m)

Gravity (m/s²)

Add atmospheric pressure (absolute pressure)

Fill in the inputs and click Calculate

Summary

Compute fluid pressure at a given depth using density, gravity, and depth — with metric and imperial unit support.

How it works

Select your unit system — metric (SI) or imperial (US).
Choose a fluid preset (water, seawater, oil, mercury) or enter a custom density.
Enter the depth (or height) of the fluid column.
Optionally adjust the gravitational acceleration value.
Toggle whether to include atmospheric pressure for absolute pressure.
The calculator instantly computes P = ρgh and displays results in multiple units.

Use cases

Engineering design of tanks, pipelines, and dams.
Scuba diving — estimating pressure at a given ocean depth.
Hydraulics and fluid mechanics coursework.
Calculating water pressure for plumbing and irrigation systems.
Submarine and underwater equipment pressure ratings.
Physics homework and lab experiment verification.
Industrial process equipment pressure calculations.
Estimating pressures for drilling and mining fluids.

Frequently Asked Questions

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Last updated: 2026-05-23 · Reviewed by Nham Vu