Buoyancy Calculator

Archimedes' Principle

A body immersed in fluid experiences an upward buoyant force equal to the weight of displaced fluid. Compare that force to the object's weight to determine whether it floats, sinks, or remains neutrally buoyant.

Buoyancy Formula

$$F_b = \rho_{\text{fluid}} V_{\text{displaced}} g$$ $$W = m g$$

If $F_b > W$ the object floats, if $F_b < W$ it sinks, and if they are equal the object is neutrally buoyant. Fresh water has density about 1000 kg/m³.

Floating Objects

A floating body submerges until displaced fluid weight equals object weight. The submerged fraction is $W / F_{b,\max}$ when the full volume could be submerged.

Frequently Asked Questions

What is buoyant force?

Buoyant force is the upward force a fluid exerts on an immersed object, equal to the weight of fluid displaced. It acts at the center of buoyancy.

Why do ships float if steel sinks?

A ship's average density—including air inside the hull—is less than water. The hull displaces enough water that buoyant force supports the total weight.

What is neutral buoyancy?

Neutral buoyancy occurs when object weight equals buoyant force. The object neither rises nor sinks, as divers aim for when hovering at a fixed depth.

Does salt water change buoyancy?

Yes. Seawater density is about 1025 kg/m³, so buoyant force is slightly higher than in fresh water for the same displaced volume.

Must the object be fully submerged?

No. Use the actual submerged volume for $V_{\text{displaced}}$. Floating objects only submerge part of their volume.

Report

Archimedes' Principle

Buoyancy Formula

Floating Objects

Frequently Asked Questions

Related Tools

Recent Visits