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FPE Calculator

FPE Calculator

Enter the Velocity and the weight of grain in the calculator and tool will find the FPE.

Velocity (ft/s - FPS):

Weight (Grains):


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An FPE calculator allows the users to find out the kinetic energy of a pellet or BB upon which it gets out from the barrel of the handgun or rifle. With the help of this calculation, you can easily find the right gun. As it defines the accurate power of an airgun.

What is FPE  (Foot Pounds of Energy)?

A foot-pound is a measurement unit of Muzzle energy. This is the energy that the pellet has when it exits from the barrel of the gun. In general, one foot-pound is the amount of energy that is used to do a task while applying the force of one pound on an object to move it one foot away. 

FPE Calculation Formula:

Below we have provided the formula that is used to calculate the FPE:

FPE = (V)^2 X (W / 450240)

  • V is the velocity of the projectile (ft/s).
  • W is the weight of the projectile (grains).

Instead of performing the calculation manually, you can use our online FPE calculator. As it lets the users calculate the FPE precisely. The user just has to add the values in specified fields and it does the rest calculation swiftly. 

How to Calculate FPE?

Let’s see the following steps to calculate the FPE conveniently!

  • First of all, determine the weight of grains.
  • After that, it’s essential to determine the correct velocity of the bullet.

Now add the values into the above-listed formula and multiply the velocity square by the weight. After that divide it with the constant and you will have the results in Foot Pounds of Energy. Our online foot pounds energy calculator also requires these two values to perform the calculations accurately. So you must have the correct values.


Let’s suppose the weight in grains is 12.5 and the velocity is 800 now How to calculate the FPE of the Airgun?


Given that:

Weight = 12.5 grains

Velocity = 800

FPE=(V)^2 X (W / 450240)

FPE = (800)^2 X (12.5 / 450240) = 8,000,000 / 450240 

FPE = 17.7683014

Working of Online FPE Calculator:

  • Firstly, add the values of the “velocity” and “weight” in the specified fields. 
  • Tap Calculate 
  • Foot pounds of energy
  • Complete steps shown


How Many Ft Lbs is 800 FPS?

Let’s imagine we have to shoot an 8-grain at 800 fps then we will calculate the square of 800 and multiply it with 8. Now divide it with the constant 450240 and you will get 11.371712. If you want to save time, then you can get the assistance of a free airgun calculator. It will let you perform the conversion in a matter of seconds. 

What is Ft Lbs of Muzzle Energy?

The calculation of muzzle energy means to determine the amount of destructive power of the pellet at which it comes out from the barrel. Its also known as Kinetic Energy and the unit used for this measurement is Foot Pound Force or ft lb. 


From the source of Foot Pounds of Energy (FPE), What is FPE?

From the source Wikipedia: Foot Pounds of Energy, Usage, Conversion.