# How To Calculate Buoyant Force

Buoyancy, or buoyant force, is based on Archimedes' Principle. This principle states, "Any object, wholly or partly immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object." Archimides' Principle is important in hydro-engineering applications, such as shipbuilding. The steps below detail how to calculate buoyant force.

### Step 1

Obtain the volume of the object on which you wish to calculate the bouyant force. We will call this value for the volume "V."

### Step 2

Determine what percentage (based on volume) of the object will be submerged in the water.

### Step 3

Convert this percentage to a decimal number. We will call this value "v." For example; if 100 percent of the object is to be submerged, v= 1.0 . If 50 percent of the object is to be submersed, v= 0.50 .

### Step 4

Substitute this value into the equation for buoyant force: FB = (V)(v) x (SPH2O) Where FB = buoyant force and SPH2O = Specific gravity of water (considered constant at 62.4 lb per cubic foot).

### Step 5

Multiply V by v, and then multiply by 62.4 in order to get the value for the buoyant force, expressed in pounds. Consider the following example of a 2-foot by 2-foot by 2 foot cube to be submersed 25 percent of the way in water. V = 2*2*2 = 8 cubic feet v = 25% = 0.25 SPH2O = 62.4 pounds per cubic foot FB = 8 **0.25** 62.4 = 124.8 pounds

That's how you calculate buoyant force, and it helps illustrate how those large ships made of steel can float. That's quite a bit of force needed to push that 2 foot cube just one fourth of the way in the water!

### TL;DR (Too Long; Didn't Read)

For laymen's calculations, the specific weight of water can be assumed to be 62.4 pounds per cubic foot, as this value does not vary significantly in normal temperature ranges.

### Cite This Article

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Smith, Anthony. "How To Calculate Buoyant Force" *sciencing.com*, https://www.sciencing.com/calculate-buoyant-force-5149859/. 24 April 2017.

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Smith, Anthony. How To Calculate Buoyant Force last modified March 24, 2022. https://www.sciencing.com/calculate-buoyant-force-5149859/