Buoyancy Calculator

Calculate buoyant force, volume, or fluid density using Archimedes' principle for floating and submerged objects

Calculate Buoyancy Parameters

Select a fluid or choose custom to enter your own density

Density of the fluid the object is immersed in

Volume of displaced fluid (submerged portion)

m/s²

Earth: 9.81 m/s², Moon: 1.62 m/s², Mars: 3.71 m/s²

Calculation Results

0.00 N
Buoyant Force
0.0000
kN
0.00
lbf
0.00
kgf
0.00e+0
dyn

Formula used: B = ρ × V × g

Displaced fluid mass: 0.000 kg

Input parameters: ρ = 1000.00 kg/m³, V = 0.000000 m³, g = 9.81 m/s²

Example Calculation

Floating Wooden Block

Scenario: Calculate buoyant force on submerged wood

Fluid: Fresh water (ρ = 1000 kg/m³)

Submerged volume: 0.03 m³

Gravity: 9.81 m/s²

Step-by-Step Solution

1. Apply Archimedes' principle: B = ρ × V × g

2. Substitute values: B = 1000 × 0.03 × 9.81

3. Calculate: B = 294.3 N

4. Result: Buoyant force = 294.3 N upward

5. Displaced fluid mass = 30 kg

Archimedes' Principle

1

Upthrust Force

Any object immersed in a fluid experiences an upward force

2

Displaced Fluid

Force equals weight of displaced fluid

3

Floating Condition

Object floats when buoyant force ≥ object weight

Common Fluid Densities

Water (fresh)1000 kg/m³
Seawater1020 kg/m³
Mercury13534 kg/m³
Oil (crude)850 kg/m³
Air (STP)1.225 kg/m³
Helium0.178 kg/m³

Applications

Ship design and stability analysis

🎈

Hot air balloons and airships

🏊

Swimming and diving equipment

🛟

Life jacket and safety equipment design

⚖️

Density measurement and material testing

🚢

Submarine ballast systems

Understanding Buoyancy and Archimedes' Principle

What is Buoyancy?

Buoyancy is the upward force that a fluid exerts on an object that is partially or completely immersed in it. This force opposes the weight of the object and can cause it to float if the buoyant force is greater than or equal to the object's weight.

Key Concepts

  • Buoyant force acts vertically upward through the center of buoyancy
  • Force magnitude equals weight of displaced fluid
  • Applies to all fluids: liquids and gases
  • Independent of object material (depends only on displaced volume)

Buoyancy Formula

B = ρ × V × g

  • B: Buoyant force (N)
  • ρ: Fluid density (kg/m³)
  • V: Volume of displaced fluid (m³)
  • g: Gravitational acceleration (m/s²)

Note: The displaced volume equals the submerged volume of the object. For floating objects, this is less than the total object volume.

Floating vs. Sinking Conditions

Floating (ρ_object < ρ_fluid)

When the object's average density is less than the fluid density, buoyant force exceeds weight, causing the object to float partially submerged.

Neutral Buoyancy (ρ_object = ρ_fluid)

When densities are equal, buoyant force equals weight. The object remains suspended at any depth without rising or sinking.

Sinking (ρ_object > ρ_fluid)

When the object's density exceeds fluid density, weight exceeds buoyant force, causing the object to sink completely.