Immersed Weight Calculator
Free calculate apparent weight of objects submerged in fluids using buoyancy principles. Get instant, accurate results with our easy-to-use calculator.
Input Parameters
Water: 1000 kg/m³, Seawater: ~1025 kg/m³
Results
Enter values to calculate
What is Immersed Weight?
Immersed weight (also called apparent weight) is the weight of an object when it's submerged in a fluid. It's less than the object's weight in air due to the upward buoyant force exerted by the fluid.
When an object is placed in a fluid, it experiences an upward buoyant force equal to the weight of the fluid it displaces (Archimedes' principle). This reduces the apparent weight measured by a scale.
The immersed weight is important in ship design, underwater construction, scuba diving, and any application where objects are weighed or handled in fluids.
Immersed Weight Formula
Where:
- • W_immersed = Apparent weight in fluid (N)
- • W_air = Weight in air (N)
- • F_buoyant = Buoyant force = ρ_fluid × V × g (N)
- • ρ_fluid = Fluid density (kg/m³)
- • V = Volume of object (m³)
- • g = Gravitational acceleration (9.81 m/s²)
How to Calculate Immersed Weight
-
1
Measure weight in air
Determine the object's weight when not submerged (W_air).
-
2
Determine object volume
Calculate or measure the volume of the object that will be submerged.
-
3
Calculate buoyant force
F_buoyant = ρ_fluid × V × g
-
4
Calculate immersed weight
W_immersed = W_air - F_buoyant
Practical Examples
Example 1: Submerged Object
An object weighs 100 N in air and has volume 0.01 m³. What is its weight when fully submerged in water?
Solution:
F_buoyant = 1000 kg/m³ × 0.01 m³ × 9.81 m/s² = 98.1 N
W_immersed = 100 N - 98.1 N
W_immersed = 1.9 N
Example 2: Floating Object
A 50 kg object with volume 0.06 m³ is placed in water. Will it float or sink? What is its immersed weight?
Solution:
W_air = 50 kg × 9.81 = 490.5 N
F_buoyant = 1000 × 0.06 × 9.81 = 588.6 N
Since F_buoyant > W_air, object floats
W_immersed = 0 N (fully supported by buoyancy)
Applications
Ship Design
Understanding how ships float and calculating cargo capacity based on displacement and buoyancy.
Scuba Diving
Calculating weight requirements for neutral buoyancy and understanding how objects behave underwater.
Laboratory
Density measurements using Archimedes' principle and determining material properties.
Construction
Underwater construction, bridge building, and understanding forces on submerged structures.
Frequently Asked Questions
Why does weight decrease in water?
The upward buoyant force opposes gravity, reducing the net downward force. The scale reads the difference between weight and buoyant force.
What if the object floats?
If buoyant force equals or exceeds weight, the object floats. Fully floating objects have zero immersed weight (they're fully supported by the fluid).
Does shape affect immersed weight?
No, only volume matters. Two objects with the same volume but different shapes have the same buoyant force and immersed weight (if fully submerged).
What about partially submerged objects?
For partially submerged objects, use only the submerged volume in the buoyant force calculation. The immersed weight depends on how much is underwater.
How does fluid density affect immersed weight?
Higher fluid density increases buoyant force, further reducing immersed weight. Objects weigh less in denser fluids like seawater compared to freshwater.