Calculator · Fluid Mechanics
Buoyant Force Calculator
A submerged body feels an upward force equal to the weight of the fluid it pushes aside. That is Archimedes' principle, and it depends on the displaced volume and the fluid density only — not on what the body is made of or how deep it sits.
Inputs
The volume of fluid actually pushed aside. For a fully submerged body that is its whole volume; for a floating body it is only the part below the surface.
Results
Buoyant force F_B = ρgV
Acts vertically upward through the centroid of the displaced volume.
| Displaced volume V | 0.2 m³ |
|---|---|
| Buoyant force F_B | 1.96133 kN |
Assumptions
- · Fully or partly submerged body in a static fluid of constant density.
Forces on the body
Buoyant force of 1.96133 kN acting upward on the displaced body.
Explore in the Lab
The same fluid also drives the pressure field and the submerged-surface views.
Technical reference
F_B = ρ g V
W = m g
F_net = F_B − W
- F_B
- buoyant force, magnitude, acting upward[N]
- ρ
- density of the fluid displaced[kg/m³]
- V
- volume of fluid displaced[m³]
- g
- gravity, 9.80665 m/s²[m/s²]
- W
- weight of the body, when supplied[N]
The buoyant force is the net effect of the hydrostatic pressure acting over the whole wetted surface. It does not depend on depth, because the pressure increases equally on the top and the bottom.
Only the displaced volume counts. A hollow hull displaces the volume its wetted shape encloses, not the volume of the material it is made from.
The comparison with weight tells you the direction of the net vertical force at this instant. It is not a stability result: whether a floating body stays upright depends on the metacentre, which this calculator does not compute.
Equal buoyant force and weight is a legitimate, fully reported answer — neutral buoyancy, not a failure.
The fluid is uniform. A layered or stratified fluid needs the displaced volume treated layer by layer.