F_b = ρ·V·g an object floats if its average density < the fluid’s density

Buoyancy: Archimedes’ upward force on a submerged object. This free calculator solves for Buoyant force, volume, density and shows every step.

The physics

Archimedes' principle: the upward buoyant force equals the weight of the fluid an object displaces. Compare that force to the object's weight — if the object's average density is less than the fluid's, it floats; if more, it sinks.

Worked example

A 0.01 m³ object fully submerged in water. F_b = 1000·0.01·9.81 = 98.1 N upward.

Common uses

Ship and submarine design, hot-air and helium balloons, hydrometers, life-jacket sizing, floating-platform engineering.

Frequently asked questions

What is the formula for Buoyancy?

Buoyancy uses the formula F_b = ρ·V·g. Archimedes’ upward force on a submerged object.

How do you calculate Buoyancy?

Choose which variable to solve for, enter the values you know (in any supported unit), and the calculator substitutes them into F_b = ρ·V·g and shows every step of the working. It can solve for Buoyant force, volume, density.

Is the Buoyancy calculator free to use?

Yes — every Physics Fundamentals calculator is completely free, with no login, no ads and no usage limits.