Buoyant Force Calculator

Calculate buoyancy from displaced fluid volume and determine whether an object floats.

About Buoyant Force Calculator

Buoyant force equals the weight of the fluid displaced, so whether something floats depends entirely on comparing its average density with the fluid’s. A steel ship floats because its average density including enclosed air is low. Density comparison is the whole test: hollow shapes float because they displace far more fluid than their material volume alone.

Formula

Buoyant Force

F_b = ρ_fluid g V_displaced

V_displaced: Volume of fluid pushed aside by the submerged part
Archimedes principle: Buoyant force equals the weight of displaced fluid

Worked example

With the default values below, Buoyant Force Calculator returns Buoyant Force of 490.500. Change any input above and every figure here is recalculated in your browser.

Inputs used

Object volumeminimum 0 m3: 0.05 m3
Object massminimum 0 kg: 40 kg
Fluid densityminimum 0.01 kg/m3: 1,000 kg/m3
Share of the object submergedaccepts 0–100 %: 100 %

Results

Buoyant Force: 490.500 N
Weight of the Object: 392.400 N
Net Upward Force: 98.100 N
Object Density: 800.00 kg/m3
Float Status: Floats — object density is below the fluid density

Step by step

1Values used
2Buoyant Force
3Buoyant Force= 490.500 N
4Weight of the Object= 392.400 N
5Net Upward Force= 98.100 N
6Object Density= 800.00 kg/m3
7Float Status= Floats — object density is below the fluid density

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Buoyant Force calculated?

F_b = ρ_fluid g V_displaced Buoyant force equals the weight of the fluid displaced, so whether something floats depends entirely on comparing its average density with the fluid’s. A steel ship floats because its average density including enclosed air is low.

Why does Buoyant Force matter?

Density comparison is the whole test: hollow shapes float because they displace far more fluid than their material volume alone.

What values do I need to enter?

This calculator takes 4 inputs: Object volume, Object mass, Fluid density, Share of the object submerged. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.