Buoyancy Calculator

Determine if an object will float or sink using Archimedes' Principle.

1. Object Properties
Object Mass (Weight)
Kilograms (kg)
Object Volume (Size)
Liters (L)
2. Fluid Type
Outcome
It Floats!
0.50 Object Density (kg/L)
50% % Submerged
5.0 L Displaced Fluid
49.0 N Buoyant Force
Freshwater

Archimedes' Principle Explained

Over 2,000 years ago, the Greek mathematician Archimedes discovered the law of buoyancy. It states that any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.

  • Density is Key: Whether an object floats or sinks doesn't depend solely on its weight, but on its density (Mass divided by Volume).
  • If Object Density < Fluid Density: The object will float. It will sink into the fluid just enough to displace an amount of fluid equal to its own weight.
  • If Object Density > Fluid Density: The object will sink. The maximum buoyant force it can generate (by fully submerging) is less than its own weight, causing it to fall to the bottom.

Example: A massive steel ship floats because its hull is filled with air, making its average density less than the density of the ocean water!