Free · Fluid mechanics calculators 💧

Displaced Fluid, Buoyant Force & Mass

Solve buoyant force, displaced fluid mass or displaced volume using fluid density and local gravity.

  • Formula & worked example
  • Private in your browser
  • No signup
Go to tool

Calculator inputs

Loading calculator…

How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

Displacing 0.1 m³ of water at 1,000 kg/m³ gives 100 kg displaced mass and 980.665 N buoyant force at standard gravity.

F_b = ρVg; displaced fluid mass = ρV

Worked example

Enter these known values and leave the other values blank.

Displaced fluid volume
.1 m³
Acceleration due to gravity
1 g
Fluid density (ρ)
1000 kg/m³
Buoyant force
980.7 N
Displaced fluid mass
100 kg

Assumptions and limitations

  • Volume means displaced fluid, equal to the submerged volume for an impermeable object. It need not equal the object’s whole volume.
  • The model assumes a stationary fluid of uniform density and gravity. It calculates buoyant force, not net force or the object’s weight.
  • Density presets are approximate and condition-dependent. Zero displaced volume gives zero force and displaced mass; zero values cannot uniquely determine density or gravity.
  • Select local gravity when available; standard gravity is exactly 9.80665 m/s².

Common questions

Does this determine whether an object floats?

Compare the object’s weight with the buoyant force available from its submerged volume. This tool does not infer the object’s mass or shape.

References

Bookify accepts zero displaced volume, buoyant force and displaced mass while retaining positive density and gravity. Feet per second squared use exactly 0.3048 meters per second squared, replacing a rounded reciprocal factor. The pound-force uses the exact international pound and standard gravity instead of the rounded captured factor. The US fluid ounce uses one 128th of the exact US liquid gallon, replacing the rounded captured reciprocal factor. The US customary cup uses one sixteenth of the exact US liquid gallon, replacing the rounded captured cup volume. Bookify replaces the captured rounded US gallon with the exact 3.785411784-liter definition. Bookify uses exact customary mass and volume definitions for density units, replacing rounded factors in the reference.

Explore fluid mechanics calculators 💧 or browse all physics calculators.