What volume should I enter?

Use the submerged or displaced volume. For a fully submerged object, this is the object's volume; for partial submersion, use only the underwater portion.

Why does a steel ship float?

The ship's average density, including the air inside the hull, can be lower than water, so it displaces enough water to balance its weight.

Does depth change buoyant force?

For an incompressible fluid and unchanged submerged volume, buoyant force does not depend on depth.

Buoyancy Calculator

Calculate buoyant force, displaced-fluid weight, apparent weight and float-or-sink behavior from fluid density, body volume, mass and gravity.

Liquid

Acceleration, m/s²

Earth standard gravity: 9.80665; classroom problems often use 10.

Known body data

Body volume

Body mass

Submersion

Buoyant force

Archimedes' principle says that the upward buoyant force equals the weight of the fluid displaced by the submerged volume.

F_{B} = ρ_{f} g V_{sub}

rho_f is fluid density, g gravity and V_sub displaced volume.

W_{apparent} = m g - F_{B}

The apparent weight is reduced by the buoyant force when the object is supported in the fluid.

Float or sink

A freely floating object displaces enough fluid for buoyancy to balance its weight. A denser object sinks unless held or supported.

Frequently Asked Questions

Sources and References

Calculations are based on the listed reference sources. Links open in a new tab.

Updated: June 2, 2026

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