Enter your bullet's weight (in grains) and velocity (in ft/s) to calculate its kinetic energy in foot-pounds (ft-lbf) and joules. The Bullet Energy Calculator uses the standard ballistics formula so you can compare muzzle energy across different cartridges, handloads, or bullet weights at a glance.
Kinetic Energy (ft-lbf)
--
Kinetic Energy (Joules)
--
Bullet Weight (lbs)
--
Bullet Momentum
--
Kinetic bullet energy is the energy a bullet carries due to its motion. It is calculated using the formula E = ½ × m × v², where m is the bullet's mass and v is its velocity. This energy determines how much force the bullet delivers upon impact, making it a key factor in assessing terminal ballistic performance.
A bullet is a kinetic projectile, meaning its destructive power comes entirely from its kinetic energy rather than explosives or other payloads. Understanding bullet energy helps shooters compare cartridges, evaluate stopping power, and assess lethality or effectiveness for hunting and self-defense applications.
Use the formula: Energy (ft-lbf) = (Bullet Weight in grains × Velocity² in ft/s) ÷ 450,240. The constant 450,240 accounts for converting grains to pounds (÷7000) and applying the kinetic energy formula (÷2 × gravity 32.174 ft/s²). This is the standard formula used in ballistics.
To find the energy at 100 yards, you need to know the bullet's velocity at that distance rather than the muzzle velocity. Use a ballistics calculator or chronograph to measure downrange velocity, then plug that velocity along with the bullet weight into this calculator to get the retained energy at 100 yards.
A typical .338 Lapua Magnum with a 250-grain bullet at 3000 ft/s produces approximately 4,995 ft-lbf (6,774 J) of muzzle energy. You can verify this by entering 250 grains and 3000 ft/s into the calculator above.
Both mass and velocity affect kinetic energy, but velocity has a greater impact because energy increases with the square of velocity. Doubling the velocity quadruples the energy, while doubling the mass only doubles it. However, heavier bullets tend to retain their velocity better at longer ranges, which can affect downrange energy.
Longer barrels generally allow more propellant gas to accelerate the bullet before it exits, resulting in higher muzzle velocity. The increase varies by caliber and powder type, but a longer barrel can add anywhere from 10 to 50 ft/s per additional inch of barrel length in many common rifle cartridges.
Muzzle energy is the kinetic energy of a bullet as it exits the barrel, measured at the muzzle. Terminal energy is the energy remaining when the bullet reaches the target. Bullets lose velocity — and therefore energy — due to aerodynamic drag over distance, so terminal energy is always lower than muzzle energy.