Water Pressure at Depth Calculator

Hydrostatic Pressure in Water

Water pressure increases with depth because the column of water above exerts weight. Divers, pool designers, and engineers use hydrostatic pressure to size equipment and ensure safety margins.

Formula

$$P = P_{atm} + \rho g h$$

Gauge pressure is $\rho g h$. Absolute pressure adds atmospheric pressure $P_{atm} \approx 101{,}325$ Pa. Density $\rho$ is 1000 kg/m³ for fresh water or 1025 kg/m³ for salt water. Gravity $g = 9.807$ m/s². Depth $h$ is in meters.

Practical Notes

Pressure doubles roughly every 10 m of fresh water depth (about 98 kPa gauge per 10 m). Salt water is about 2.5% denser, so pressure builds slightly faster. Use feet input for imperial measurements — 1 ft ≈ 0.3048 m.

Frequently Asked Questions

What is the pressure at 10 m depth in fresh water?

Gauge pressure is about 98.1 kPa. Absolute pressure is about 199.4 kPa (including 101.3 kPa atmospheric).

Why is salt water pressure higher?

Salt water density (1025 kg/m³) exceeds fresh water (1000 kg/m³). More mass per unit volume means greater hydrostatic pressure at the same depth.

What is gauge vs absolute pressure?

Gauge pressure measures above atmospheric. Absolute pressure includes atmospheric — it is what a total pressure sensor reads at depth.

How do I convert feet to meters?

Multiply feet by 0.3048. For example, 33 ft ≈ 10.06 m. This calculator handles the conversion automatically.

Does water temperature affect pressure?

Density changes slightly with temperature, but for most practical depths the effect is small. This tool uses standard fresh/salt water densities.

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Water Pressure at Depth Calculator

Hydrostatic Pressure in Water

Formula

Practical Notes

Frequently Asked Questions

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