Muzzle Velocity & Energy Calculator
Enter a bullet's grain weight and muzzle velocity to find kinetic energy in both ft-lb and joules, SI momentum, IPSC/USPSA power factor, and an in-vacuum trajectory arc at any launch angle.
gr
ft/s
°
Kinetic energy at the muzzle
- 1
Velocity squared
v² = 1,000² = 1,000,000 - 2
Mass × velocity²
147 gr × 1,000,000 = 147,000,000 - 3
Muzzle energy
(mass × v²) ÷ 450,436 = 147,000,000 ÷ 450,436 = 326Standard US formula: KE (ft-lb) = mass(gr) × v²(fps) ÷ 450,436.
How does this calculator work?
Enter bullet mass (grains) and muzzle velocity (ft/s): KE = (gr × v²) / 450,436 ft-lb; multiply by 1.356 for joules. Also shows kg·m/s momentum, IPSC power factor, and a vacuum trajectory arc. Air drag is ignored — real range is much shorter than the arc shown.
Formula
How this is calculated
Kinetic energy is the most widely reported ballistic figure of merit because it governs terminal performance. The US formula derives directly from KE = ½mv²: converting grains to pounds (÷ 7,000) and pounds to slugs (÷ 32.174) before squaring the velocity yields energy in foot-pounds, equivalent to the shortcut (mass_gr × v²_fps) / 450,436. Multiplying by 1.35582 gives the SI value in joules.
The IPSC/USPSA power factor is simply mass(gr) × velocity(fps) / 1,000 — the raw metric before the sanctioning body applies division-specific cutoffs (Major ≥ 160, Minor ≥ 125 in most divisions). This calculator gives the number; whether it qualifies depends on your division and official chronograph results.
The trajectory arc uses the simple vacuum parabola x(t) = v·cos θ·t, y(t) = v·sin θ·t − ½g·t². Real bullets decelerate sharply due to aerodynamic drag: actual range and maximum height are a fraction of the vacuum figures shown. The arc here illustrates the shape of flight and the effect of launch angle — for a field-use firing solution, consult a G1/G7 ballistic-coefficient drag model.
Frequently asked questions
Muzzle energy (kinetic energy at the barrel exit) measures how much work a bullet can do on a target. It is expressed in foot-pounds in the US and joules in SI. Higher energy generally means greater penetration and terminal effect, though bullet construction also plays a major role.
For the same propellant charge, lighter bullets reach higher velocity while heavier bullets retain energy better over distance. The optimal grain weight depends on the calibre, barrel twist rate and intended use — this calculator shows the energy for any mass/velocity combination from manufacturer or chronograph data.
Air drag cuts real-world range to a small fraction of the vacuum figure shown. The parabola here illustrates the geometric shape of flight — for accurate external ballistics, including wind, drag and spin drift, use a dedicated ballistic solver with the bullet's ballistic coefficient.
Also known as
TG we-Calculate Editorial Team. (2026). Muzzle Velocity & Energy Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/muzzle-velocity-calculator
TG we-Calculate Editorial Team. "Muzzle Velocity & Energy Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/muzzle-velocity-calculator.
TG we-Calculate Editorial Team, "Muzzle Velocity & Energy Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/muzzle-velocity-calculator
@misc{wecalculate_muzzle_velocity_calculator, title = {Muzzle Velocity & Energy Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/muzzle-velocity-calculator}}, year = {2026}, note = {TG we-Calculate} }
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