Bullet Energy Calculator
Use our bullet energy calculator to calculate bullet energy (ft-lb) from bullet mass (gr) and bullet velocity (ft/s). Includes the bullet energy formula and a simple example showing how to calculate energy of a bullet.
What Is Bullet Energy?
Bullet energy usually refers to kinetic energy, which is the energy an object has due to motion. For a projectile, kinetic energy increases with mass and increases very rapidly with velocity because velocity is squared.
Bullet energy is commonly expressed in foot-pounds (ft-lb) in the US. This value can help compare the relative energy of different projectile mass and velocity combinations.
This calculator uses bullet mass in grains (gr) and bullet velocity in feet per second (ft/s) to compute kinetic energy in ft-lb.
Bullet Energy Formula
Kinetic energy is KE = 1/2 · m · v^2. When mass is entered in grains and velocity in ft/s, a standard conversion constant is used to output energy in foot-pounds (ft-lb).
The constant 450240 converts grains and ft/s into foot-pounds.
Velocity has a large impact because it is squared.
How to Calculate Bullet Energy
- 1
Enter bullet mass in grains (gr).
- 2
Enter bullet velocity in feet per second (ft/s).
- 3
The calculator applies E = (m × v²) ÷ 450240 to return energy in foot-pounds (ft-lb).
Frequently Asked Questions
Use kinetic energy. In common US units: E(ft-lb) = (mass in grains × velocity(ft/s)²) ÷ 450240.
It depends on the bullet’s mass and velocity. Higher velocity increases energy a lot because energy scales with v².
Because energy is proportional to velocity squared. Doubling velocity increases energy by 4×, while doubling mass increases energy by 2×.
This calculator outputs foot-pounds (ft-lb), a common unit of energy in the US.
Not by itself. Energy over distance requires velocity at that distance (or a model for how velocity changes). If you enter a different velocity, the calculator will compute the corresponding energy for that point.