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Density & Buoyancy Calculator
Calculate material density, submerged displaced fluid volume, buoyant force, and float-or-sink equilibrium using Archimedes' principle.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Object Density & Status
Buoyant Force (Fb = ρ · V · g)
Submerged Fraction
How it works
- Select the surrounding fluid medium (Fresh Water, Sea Water, Oil, Glycerin, Mercury, or Air).
- Enter the object's mass and total physical volume in standard units (kg, grams, lbs, m³, Liters, cm³).
- The calculator computes object density (ρ = m/V) and compares it against the fluid density.
- Review the buoyant force (Newtons), float-or-sink determination, submerged volume percentage, and apparent submerged weight.
The formula
Density: ρ = Mass / Volume
Buoyant Force: Fb = ρ_fluid × V_displaced × g (g = 9.80665 m/s²)
Submerged Fraction (for floating objects): V_sub / V_total = ρ_object / ρ_fluid
FAQ
What is Archimedes Principle of Buoyancy?
Archimedes' principle states that any object completely or partially submerged in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object: Fb = ρ_fluid × V_submerged × g.
Why does a floating object displace its weight rather than its volume?
When an object floats in static equilibrium, the upward buoyant force exactly equals the downward gravitational force (weight). Therefore, it sinks only deep enough to displace a volume of fluid whose mass equals the object's total mass.
What is apparent submerged weight?
For dense sinking objects (ρ_object > ρ_fluid), the apparent weight felt underwater equals the object's true weight in air minus the upward buoyant force: W_apparent = F_gravity − F_buoyant.
Why is salt water easier to float in than fresh water?
Sea water has a higher density (approx 1,025 kg/m³) than fresh water (1,000 kg/m³) due to dissolved salts, which produces a larger buoyant force for the same volume of displaced water.
How we compare
| Feature | Online Tool Store | Physics textbook tables | Manual formula |
|---|---|---|---|
| Submerged volume fraction & percentage calculation | ✓ | ✗ | ✗ |
| Apparent underwater weight force (N) | ✓ | Partial | ✗ |
| Pre-loaded fluid density presets (Sea water, Oil, Air) | ✓ | ✓ | ✗ |