How to Calculate Buoyancy
What is Buoyancy?
Buoyancy (upthrust) is the upward force exerted by a fluid on a submerged or partially submerged object. Archimedes' principle states: buoyant force = weight of fluid displaced by the object.
Step-by-Step Guide
- 1Buoyant force (F_b) = ρ × g × V_displaced
- 2ρ = fluid density (water ≈ 1,000 kg/m³, seawater ≈ 1,025 kg/m³)
- 3Object floats if its average density < fluid density
- 4Apparent weight = Actual weight − Buoyant force
Worked Examples
Input
2 litre object fully submerged in water
Result
Buoyant force = 19.62 N (≈ 2kg weight)
1000×9.81×0.002=19.62 N
Ready to calculate? Try the free Buoyancy Calculator
Try it yourself →