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Buoyancy Calculator (Archimedes’ Principle)

Applies Archimedes’ principle to an object in a fluid.

Fresh water is about 1,000 kg/m³, and seawater about 1,025.

m/s²

Standard Earth gravity is 9.80665. The Moon is about 1.62 and Mars about 3.71.

Buoyant force when fully submerged
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Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.

Weight —
Net upward force when submerged —
Object density —
Share below the surface when floating — %
Result —

The formula

F = ρ V g

The buoyant force equals the weight of the fluid displaced. A floating object displaces only enough fluid to match its own weight.

What to watch out for

For hollow objects, use the outer volume and the total mass, as that is what displaces water.

Frequently Asked Questions

How much does displacing 10 L of water lift?

98.07 N, enough to hold up 10 kg.

How much of an iceberg is below the water?

Using 917 kg/m³ for ice and 1,025 for seawater, about 89%.