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How It Works
Hydrostatic pressure (P = ρgh) increases linearly with depth because the weight of fluid above pushes down on the fluid below. This calculator solves for any of the four variables: pressure, density, gravitational acceleration, or depth. The result gives gauge pressure; add atmospheric pressure (101,325 Pa) for absolute pressure.
Example Problem
A scuba diver descends to 20 m in seawater (density 1,025 kg/m³). What is the gauge pressure at that depth?
- P = ρ × g × h = 1,025 × 9.81 × 20
- P = 201,105 Pa (about 2 atm gauge, or 3 atm absolute)
Frequently Asked Questions
How do you calculate fluid pressure at a given depth?
Multiply the fluid density (ρ) by gravitational acceleration (g, usually 9.81 m/s²) by the depth (h). For water at 10 m depth: 1,000 × 9.81 × 10 = 98,100 Pa.
What is the difference between gauge and absolute pressure?
Gauge pressure is the pressure above atmospheric. Absolute pressure includes atmospheric pressure (about 101,325 Pa at sea level). Absolute = gauge + atmospheric.
Does the shape of a container affect fluid pressure?
No. Hydrostatic pressure depends only on depth, fluid density, and gravity — not the shape or total volume of the container. This is known as the hydrostatic paradox.
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