How this calculator works
Pressure increases downward in a stationary fluid, so the underside of a submerged body experiences a greater upward force than the downward force on its top. The net force equals displaced fluid weight. Use the actual fluid density, not the object density. A floating body adjusts its immersion until buoyancy balances its weight. The reference density table gives rounded textbook values, not a temperature correction model.
Formula
B = rho g V; displaced fluid mass = rho V = B/g. Standard gravity is 9.80665 m/s2. Gas buoyancy follows the same law if density is adequately uniform.
Worked example
Displacing 0.01 m3 of water at 1000 kg/m3 displaces 10 kg and produces 98.0665 N at standard gravity. Displacing 0.02 m3 produces 196.133 N.
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Frequently asked questions
Does an object that sinks experience buoyancy?
Yes. It still displaces fluid, but its weight exceeds the buoyant force if it sinks without support.
Which volume do I enter for a floating object?
Enter only the volume below the fluid surface, including any watertight enclosed space that displaces fluid.
Can I use this for a balloon?
Yes, using the surrounding air density and the external displaced volume. Subtract the balloon and contained-gas weights to find net lift.