Buoyancy Calculator
Upthrust on a submerged body, the net weight in the fluid and how much of it floats below the surface.
Results
Buoyant force
490.333
N
Mass
50.000
kg
Force
-147.100
N
Submerged fraction
70.00
%
What this tool does
The upward force equals the weight of the fluid pushed aside, which is Archimedes' whole idea and the reason a steel ship floats while a steel bar sinks — the ship displaces far more water than it weighs. An object less dense than the fluid floats with exactly its density ratio submerged.
Formula
F = ρ × g × V (Archimedes' principle)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
v | Volume | m³ |
rf | Fluid density | kg/m³ |
ro | Density of the object | kg/m³ |
FB | Buoyant force | N |
MD | Mass | kg |
NW | Force | N |
SU | Submerged fraction | % |
Worked example
- Volume0.05 m³
- Fluid density1000 kg/m³
- Density of the object700 kg/m³
- Buoyant force490.333 N
- Mass50.000 kg
- Force-147.100 N
- Submerged fraction70.00 %
Limitations
- The formula assumes ideal conditions: no friction losses, no air resistance and no efficiency losses unless you enter them.
- Density changes with temperature, moisture and composition. Use a value from the supplier's data sheet whenever precision matters.