Physics

FPE Calculator (Foot-pounds of Energy)

Find muzzle energy in foot-pounds from grains and feet per second.

Calculated Output

Energy (ft·lb) 364.23

Formula: FPE = grains × fps² ÷ 450,240

Step-by-Step Breakdown

1. Values used:

2. Projectile weight = 124 gr

3. Velocity = 1,150 fps

5. Energy = 364.23ft·lb

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The math behind it

FPE = grains × velocity² ÷ 450,240. The constant folds in the grain-to-pound and unit conversions.

124 gr at 1150 fps → about 364 ft·lb.

How many grains in a pound?

7000 grains make one pound.