Enter the weight (grains) and the velocity (fps) into the calculator to determine the FPE. This calculator can also determine the weight or velocity if the other variables are known.

FPE Formula

The following formula is used to calculate the foot-pounds energy (FPE) of a projectile.

FPE = V^2 * W / 450240
  • Where FPE is the foot-pounds of energy
  • V is the velocity of the projectile (ft/s)
  • W is the weight of the projectile (grains)

To calculate FPE, square the project velocity, multiply the result by the weight in grains, then divide by 450240.

FPE Definition

FPE is short for foot-pounds of energy. This term is used to describe the kinetic energy contained in a projectile.

Example Problem

How to calculate FPE?

  1. First, determine the velocity of the projectile.

    For this example, the projectile is moving at 700 ft/s.

  2. Next, determine the weight of the projectile.

    The projectile, a pellet, in this case, weighs 12.5 grains.

  3. Finally, calculate the FPE.

    Using the formula above, the foot-pounds of energy is calculated as:
    FPE = V^2 * W / 450240
    FPE = 700*700&12.5/450240
    FPE = 13.603