About the Buoyancy Calculator
What is the Buoyancy Calculator?
Archimedes' principle: a submerged object is pushed up by a force equal to the weight of fluid it displaces. This buoyancy calculator compares that force with the object's weight.
If the object is less dense than the fluid, it floats, with the fraction below the surface equal to the ratio of densities.
How to use the Buoyancy Calculator
- Object Volume (litres) (sample: 10)
- Object Mass (kg) (sample: 5)
- Fluid (sample: Fresh water (1,000 kg/m³))
- Custom Fluid Density (kg/m³) (sample: 1,000)
- Press Calculate Buoyancy (results also refresh as you type). The result card shows the Buoyant Force (fully submerged), along with Object weight, Result, Share of volume below the surface and Object density.
Formula used
F_b = ρ_fluid × g × V
- Floats if = object density < fluid density
- Fraction submerged = ρ_object ÷ ρ_fluid
Sea water is denser than fresh water, so ships float slightly higher at sea.
Worked example
These are the sample values already filled in the calculator above, and the result it returns for them:
| Input | Sample value |
|---|---|
| Object Volume (litres) | 10 |
| Object Mass (kg) | 5 |
| Fluid | Fresh water (1,000 kg/m³) |
| Custom Fluid Density (kg/m³) | 1,000 |
| Result | Value |
|---|---|
| Buoyant Force (fully submerged) | 98.067 N |
| Object weight | 49.033 N |
| Result | Floats |
| Share of volume below the surface | 50% |
| Object density | 500 kg/m³ |
Tips for using the Buoyancy Calculator
- Ships float because their hull encloses air, lowering their average density.
- About 90% of an iceberg is under water (ice 917 vs sea water 1,025 kg/m³).