Fpe Calculator
Calculate the Foot-Pounds of Energy (FPE) of a projectile based on its weight and velocity. Useful for airgun and firearm enthusiasts.
Published by:
isCalculator Editorial Team
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How to use this tool?
How to Use the FPE Calculator
- Enter Projectile Weight – Type the weight of your projectile in grains (e.g., 15.9).
- Enter Velocity – Type the velocity in feet per second (fps) (e.g., 900).
- Click "Calculate FPE" – The tool will compute the energy in foot-pounds (FPE).
- Read the Result – The FPE value appears in green. The formula used is shown below it for verification.
Important: Both inputs must be positive numbers. The calculator uses the standard formula: FPE = (weight in grains × velocity² in fps) / 450240.
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Frequently Asked Questions
FPE stands for Foot-Pounds of Energy, a unit of energy commonly used to measure the kinetic energy of projectiles like bullets and pellets.
The formula is FPE = (Weight in grains × Velocity in fps squared) / 450240.
The constant 450240 converts grains and fps to foot-pounds. It comes from the conversion factors: 1 lb = 7000 grains, and 1/2 * m * v^2 in imperial units.