Muzzle Energy Calculator

The kinetic energy formula squares velocity but only multiplies weight linearly (KE = 1/2 x mass x velocity^2), so a given percentage increase in velocity produces a larger percentage increase in energy than the same percentage increase in weight would. In practice, though, bullet weight also spans a much wider real-world range than muzzle velocity does -- from light airgun pellets to heavy rifle bullets -- so both inputs end up mattering substantially to the final energy figure, just through different mechanisms.

450,240 is the standard conversion constant for computing kinetic energy in foot-pounds directly from bullet weight in grains and velocity in feet per second -- Energy = (weight x velocity^2) / 450,240. It bundles the kinetic-energy formula's 1/2 factor together with the unit conversion from grains to pounds and squared feet-per- second, so the result comes out directly in foot-pounds without a separate conversion step.

Power Factor (bullet weight in grains x velocity in fps, divided by 1,000) is a USPSA competition scoring metric proportional to momentum, not kinetic energy -- it scales linearly with both weight and velocity rather than squaring velocity. Because of that difference, a heavier bullet at modest velocity and a lighter bullet at high velocity can have similar Power Factor scores while having noticeably different muzzle energy.

Yes. Since energy scales with velocity squared but momentum (weight x velocity) scales linearly with each, a lighter bullet driven faster and a heavier bullet driven slower can land at the same energy figure while carrying meaningfully different momentum. This is part of the classic "light and fast" versus "heavy and slow" tradeoff in cartridge and bullet selection.