Submerged Body Apparent Weight Calculator

Calculate buoyant force and apparent weight of a fully submerged object.

Wapp = (ρbody − ρfluid)Vg

Body density ρbody (kg/m³)

Fluid density ρfluid (kg/m³)

Body volume V (m³)

Gravity g (m/s²)

Enter valid values in all required fields.

What this formula means

A submerged object experiences an upward buoyant force equal to the weight of displaced fluid. Apparent weight is the object weight minus buoyancy and may become negative when the object is less dense than the fluid.

Use apparent weight for underwater lifting, material density experiments, diving systems, ballast, and submerged equipment. The result should be interpreted with consistent units and with the assumptions of the underlying model in mind.

Worked example

A 0.01 m³ steel body in water has apparent weight about 667 N.

Applications

Use apparent weight for underwater lifting, material density experiments, diving systems, ballast, and submerged equipment. It is also useful as an independent check when comparing hand calculations, laboratory measurements, simulations, or preliminary engineering estimates.

Assumptions and common mistakes

Important: This formula assumes the object is fully submerged and uses its displaced external volume, not merely the solid-material volume when cavities are present.

Use SI units unless the field label states otherwise. Keep significant figures appropriate to the accuracy of the inputs, and do not treat a simplified calculator as a replacement for codes, detailed design standards, or professional review.

Frequently asked questions

What equation does this calculator use?Wapp = (ρbody − ρfluid)Vg. The calculator evaluates the displayed relationship using the values entered above.

Are the results unit-sensitive?Yes. The input labels use SI units so the displayed output follows the corresponding SI unit.

Can I use this for engineering design?Use it for learning and preliminary checks. Final designs require validated data, applicable standards, safety factors, and professional judgment.