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What This Calculator Does

This tool calculates the buoyant force acting on an object submerged in a fluid, based on Archimedes’ principle, and compares it against the object’s weight to indicate whether it would float or sink.

The Formula

Buoyant force is calculated as F = ρ × V × g, where F is the buoyant force in newtons, ρ (rho) is the density of the fluid in kg/m³ (fresh water is about 1000 kg/m³, seawater about 1025 kg/m³, air about 1.225 kg/m³), V is the volume of fluid displaced by the object in cubic meters, and g is gravitational acceleration (9.80665 m/s²). The net force is the buoyant force minus the object’s weight (mass × g).

Why It Matters

Archimedes’ principle explains why objects float or sink: if the buoyant force exceeds the object’s weight, it floats; if the weight exceeds the buoyant force, it sinks. This same principle governs how ships, submarines, and hot air balloons are designed.

  • Enter the submerged volume, which for a floating object is only the portion below the surface, not its full volume.
  • Provided for general educational and planning purposes.
Last reviewed August 2026