Buoyancy Calculator

This calculator finds the buoyant force on an object using Archimedes' principle, the law that explains why things float and how much they can support. When an object is placed in a fluid, whether fully submerged or partly floating, the fluid pushes up on it with a force called buoyancy, or upthrust. Archimedes' famous insight was that this upward force equals the weight of the fluid the object displaces, pushes out of the way. So a steel ship floats, despite steel being denser than water, because its hull shape displaces a huge volume of water, and the weight of that displaced water exceeds the ship's own weight. The buoyant force depends on the density of the fluid, the volume displaced, and gravity. This tool computes it. You enter the fluid's density, the volume of fluid displaced, and gravity, and the calculator returns the buoyant force in newtons, along with the mass of fluid displaced, the equivalent in kilograms of force, and a note of the fluid. The results update as you type, so you can explore how displacing more volume or using a denser fluid increases the lift. Use it for physics problems, for understanding floating, ships and submarines, for hot-air and diving calculations, or for engineering. The principle is wonderfully simple: buoyant force equals fluid density times displaced volume times gravity. An object floats if this buoyant force can equal its weight, sinks if its weight exceeds the maximum buoyancy when fully submerged, and a submarine or fish adjusts its effective volume or density to rise and sink. The buoyant force is also exactly the apparent loss of weight you feel when lifting something underwater, which is why heavy objects feel lighter in a pool.

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Archimedes: buoyant force = fluid density x volume displaced x gravity. Water is ~1000 kg/m³, seawater ~1025. The force equals the weight of fluid displaced.