Calculate muzzle energy, momentum, and power factor from bullet mass and velocity. Compare calibers and check competition thresholds.
Muzzle energy is the kinetic energy of a bullet as it leaves the barrel and is a practical indicator of a cartridge's power. Measured in foot-pounds or joules, it is often used to compare load performance, recoil expectations, and basic suitability for different shooting tasks.
This calculator computes muzzle energy from bullet mass and velocity in either imperial or metric units. It also calculates momentum, power factor for competition shooting, Taylor Knockout factor for hunting-oriented comparisons, and Mach number. Preset buttons for common calibers load typical factory data quickly.
A comparison table shows energy, momentum, and power factor for common cartridges from .22 LR to .50 BMG, while the competition table checks whether a load meets USPSA, IPSC, or IDPA power-factor thresholds.
Handloaders, competitive shooters, and hunters often need the same round expressed in different ways: energy, momentum, and power factor. Keeping those metrics together makes it easier to compare loads without doing the same conversion work repeatedly.
The comparison tables are most useful when you want to see how a load stacks up against familiar cartridges or competition thresholds.
KE (ft-lbs) = (mass_grains × velocity_fps²) / 450,240. Momentum (lb·s) = mass_kg × velocity_m/s × 0.2248. Power Factor = mass_grains × velocity_fps / 1000.
Result: 356 ft-lbs, PF 135.7
A standard 9mm Luger load (115 gr at 1,180 fps) produces 356 ft-lbs of muzzle energy and a power factor of 135.7, meeting USPSA Minor requirements.
Muzzle energy alone does not fully describe terminal performance. Bullet construction (hollow point, FMJ, bonded), sectional density, and expansion characteristics matter as much as raw energy. A well-designed 9mm hollow point at 356 ft-lbs can be more effective than a poorly designed .45 ACP at 404 ft-lbs because of controlled expansion.
Recoil energy is proportional to bullet momentum (not energy). This is why a .45 ACP (high momentum, moderate energy) has noticeably more recoil than a 9mm (moderate momentum, similar energy). Competitive shooters choose minimum-power-factor loads to reduce recoil and improve split times.
For home defense, select ammunition with 300-450 ft-lbs and proven hollow point performance. For hunting, match minimum energy requirements to the game: 1,000+ ft-lbs for deer, 1,500+ for elk, 2,000+ for moose. For competition, optimize for the minimum power factor that meets division rules — every excess grain of powder is wasted recoil.
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Muzzle energy is the kinetic energy of a bullet at the moment it exits the barrel. It equals ½mv² and is typically expressed in foot-pounds (ft-lbs) or joules.
Power factor (PF) = bullet weight (grains) × velocity (fps) / 1000. Competition shooting organizations use PF to classify loads — e.g., USPSA Major requires PF ≥ 165.
Not necessarily. Higher energy means more recoil. For hunting, you need enough energy for ethical kills, but excessive energy adds recoil without benefit. For competition, you want to just meet the power factor threshold.
The Taylor KO factor (developed by John "Pondoro" Taylor for African big game) accounts for bullet diameter in addition to mass and velocity. It is an empirical index of stopping power for large animals.
Heavier bullets are slower (for the same powder charge) but carry more momentum. Lighter bullets are faster with higher energy, but momentum may be lower. The optimal balance depends on the application.
The .45 ACP fires a much heavier bullet (230 gr vs 115 gr) but at lower velocity (830 vs 1180 fps). Since KE depends on v² but momentum on v, the heavy slow bullet has more momentum but less energy.