Ballistic Energy Calculator
Calculate the kinetic energy of a projectile in foot-pounds (ft-lbs) or Joules from its mass and velocity. Supports grains, grams, ounces, and pounds for mass, and fps, m/s, mph, and km/h for velocity.
Published by:
isCalculator Editorial Team
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How to use this tool?
This calculator computes the kinetic energy of a projectile using the formula KE = ½ × mass × velocity².
- Enter the mass of the projectile in the first field. You can choose between kilograms (kg), grams (g), or grains (gr).
- Enter the velocity of the projectile in the second field. Options are meters per second (m/s), feet per second (fps), or kilometers per hour (km/h).
- Click Calculate Energy to get the result.
The result shows the kinetic energy in Joules along with the formula breakdown. All inputs must be positive numbers—the calculator will highlight any invalid entries.
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Frequently Asked Questions
Ballistic energy is the kinetic energy of a moving projectile, calculated as KE = 0.5 × mass × velocity². In the United States, shooters and hunters almost universally express it in foot-pounds (ft-lbs), the energy required to lift one pound by one foot. One foot-pound equals about 1.3558 Joules.
There are exactly 7,000 grains in one pound. This calculator converts automatically: it multiplies your grain value by 0.00006479891 to get kilograms, then computes energy in Joules before converting to foot-pounds. For example, a 150-grain bullet is about 0.02143 lb.
Common minimum guidelines are around 1,000 ft-lbs for deer-sized game and 1,500+ ft-lbs for larger game like elk. A .308 Winchester with a 150-grain bullet at 2,800 fps produces roughly 2,600 ft-lbs, while a .45 ACP with a 230-grain bullet at 850 fps produces about 370 ft-lbs.