Buoyancy Force Calculator
buoyancy force calculator. Get instant, accurate results. Enter values for instant results with step-by-step formulas.
Reviewed for accuracy by Manoj Kumar, Mathematics Educator
Buoyancy Force Calculator
Calculator
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Formula: F_b = ρ_fluid × V_displaced × g
Worked example — 4905 N
Formula
F_b = ρ_fluid × V_displaced × g
Archimedes principle: buoyant force equals the weight of displaced fluid.
Worked Examples
Example 1: Wooden block
Problem:ρ=1000 kg/m³, V=0.5 m³
Solution:Fb=1000×0.5×9.81=4905 N
Result:4905 N
Frequently Asked Questions
What is buoyancy force?
Buoyancy force (F_b) is the upward force exerted by a fluid on a submerged or floating object. It equals the weight of the displaced fluid: F_b = ρ_fluid × V_displaced × g, where ρ is density (kg/m³), V is volume (m³), and g = 9.81 m/s².
How do you calculate buoyancy force?
Apply Archimedes' principle: F_b = ρ_fluid × V_displaced × g. For example, a 0.5 m³ object submerged in water (ρ = 1000 kg/m³): F_b = 1000 × 0.5 × 9.81 = 4905 N upward.
What units does the buoyancy calculator use?
Fluid density is entered in kg/m³ (water ≈ 1000, seawater ≈ 1025, air ≈ 1.225). Displaced volume is in m³. The resulting buoyant force is in Newtons (N). Object mass is in kg, and weight is calculated as mg in Newtons.
What is a real-world example of buoyancy?
A steel ship floats because its hollow hull displaces a large volume of water. A ship of mass 50,000,000 kg must displace 50,000,000 / 1025 ≈ 48,780 m³ of seawater to generate enough buoyant force (about 490 MN) to balance its weight.
Background & Theory
Buoyancy and Density, by Fluid
Whether an object floats depends entirely on comparing its average density to the fluid's density — an object less dense than the fluid it's placed in floats with part of its volume above the surface, while a denser object sinks. This calculator applies Archimedes' principle directly: the buoyant force always equals the weight of the fluid displaced, regardless of the submerged object's own weight or shape.
| Fluid | Density (kg/m³) |
|---|---|
| Fresh water (4°C) | 1,000 |
| Seawater | 1,020-1,030 |
| Air (sea level, 20°C) | ~1.2 |
| Vegetable oil | ~920 |
| Mercury | 13,534 |
A steel ship floats not because steel is less dense than water (it isn't — steel is about 7,850 kg/m³) but because the hull's hollow shape means the ship's overall AVERAGE density, hull plus air-filled interior, is less than water. That's also why a solid steel block sinks instantly while a steel ship, carrying the same mass spread over a much larger displaced volume, stays afloat.
Reviewed for accuracy by Manoj Kumar, Mathematics Educator · Editorial policy
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