Pressure at Depth Calculator NZ

This calculator works out the pressure at a given depth in a fluid, the hydrostatic pressure caused by the weight of the fluid above. As you go deeper into water or any fluid, the column of fluid above you grows heavier, and the pressure it exerts increases steadily with depth. This is why your ears hurt at the bottom of a swimming pool, why submarines and dam walls must be built to withstand enormous forces, and why divers manage their descent carefully. The pressure from the fluid alone, the gauge pressure, is simply the fluid density times gravity times the depth. The absolute pressure adds the atmospheric pressure pushing down on the surface as well. This tool computes both. You enter the fluid density, the depth, and gravity, and the calculator returns the gauge pressure in kilopascals, the absolute pressure including the atmosphere, the pressure in atmospheres for an intuitive scale, and the depth itself. The results update as you type. Use it for diving and water-sports planning, for tank and dam engineering, for physics study, or to understand how pressure builds underwater. The gauge pressure is the density times gravity times depth, and the absolute pressure adds about 101 kilopascals of atmospheric pressure at the surface. A useful rule the numbers reveal is that in water, pressure rises by roughly one atmosphere for every ten metres of depth, so a diver at ten metres feels about double the surface pressure, at twenty metres about triple, and so on. Fresh water has a density near 1,000 kilograms per cubic metre and seawater slightly more at about 1,025, so seawater pressure builds a touch faster. The calculation assumes a fluid of constant density, an excellent approximation for water at the depths divers and most structures encounter.

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Gauge pressure = density x gravity x depth. Absolute adds atmospheric (~101.325 kPa). In water, pressure rises ~1 atm per 10 m. Assumes constant density.