Displaced Fluid Volume Calculator
The displaced fluid volume calculator applies Archimedes' principle to determine the volume of fluid displaced by a submerged or floating object, the resulting buoyant force, and whether the object will float or sink. Archimedes discovered that any object placed in a fluid experiences an upward buoyant force equal to the weight of the fluid it displaces. This principle governs ship design, submarine ballast systems, density measurement of irregular solids, and the behavior of balloons in air. Enter the object's dimensions and density alongside the fluid density to instantly determine buoyancy, displaced volume, and floating behavior.
Archimedes principle formula
Buoyant force: F_b = rho_fluid * g * V_displaced
Object weight: W = rho_obj * g * V_obj
Floats if: rho_obj less than rho_fluid
Equilibrium fraction submerged = rho_obj / rho_fluid
Common fluid densities (kg/m^3)
- Fresh water at 4 degC: 1,000 kg/m^3
- Salt water: 1,025 kg/m^3
- Air at sea level: 1.225 kg/m^3
- Mercury: 13,600 kg/m^3
- Engine oil: 870 to 920 kg/m^3
Displaced volume: frequently asked questions
What is Archimedes' principle?
Archimedes' principle states that a body immersed in a fluid experiences a buoyant force equal to the weight of the fluid it displaces. Buoyant force = rho_fluid * g * V_displaced. If this buoyant force exceeds the object's weight, the object floats; if less, it sinks.
How do I calculate displaced volume for a partially submerged object?
The displaced volume equals the volume of the object below the fluid surface. For a fully submerged object, displaced volume equals the total object volume. For a floating object at equilibrium, the displaced fluid weight equals the object's total weight: rho_fluid * V_disp * g = m_object * g, so V_disp = m_object / rho_fluid.
What is specific gravity?
Specific gravity is the ratio of a material's density to water's density (1000 kg/m^3 at 4 degC). An object with specific gravity less than 1 floats in water; greater than 1 sinks. Steel has SG = 7.8, aluminum = 2.7, wood = 0.4 to 0.9, ice = 0.92.
How is buoyant force used in ship design?
Ships are designed so the hull displaces a volume of water whose weight equals the ship's total weight (including cargo). The waterline shows the displacement level. Adding cargo sinks the ship lower until new equilibrium is reached. The Plimsoll line marks the maximum safe displacement.
What is the difference between displacement and draft?
Displacement is the mass (or weight) of fluid displaced, equal to the ship's total weight. Draft is the vertical distance between the waterline and the bottom of the hull. A deeper draft means more displacement. Naval architects calculate displacement at various drafts to create hydrostatic tables.
Official sources
- NIST: NIST Weights and Measures Division.
- US DOT: US Department of Transportation - Maritime Standards.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.