Muzzle Velocity Calculator

Muzzle Velocity from Kinetic Energy

Muzzle velocity is the speed of a projectile as it leaves the barrel. When bullet mass and kinetic energy are known, velocity follows directly from the energy equation.

Formula

$$v = \sqrt{\frac{2 \times KE}{m}}$$

$KE$ is kinetic energy in joules and $m$ is bullet mass in kilograms. This calculator accepts mass in grains and energy in foot-pounds, converting internally to SI units.

Unit Conversions

One grain equals 64.79891 milligrams. One foot-pound equals 1.3558 joules. A 55-grain bullet with 1300 ft·lb of energy has a muzzle velocity near 995 m/s (3260 ft/s).

Limitations

This formula assumes all propellant energy transfers to the bullet with no losses. Real firearms lose energy to friction, gas escape, and barrel heat. Related tools: Projectile Motion Calculator and Kinetic Energy Calculator.

Frequently Asked Questions

What is a grain?

A grain is a unit of mass equal to 1/7000 of a pound, or about 64.8 milligrams. Bullet weights are commonly listed in grains.

What is typical muzzle velocity?

Handgun rounds often exit between 300 and 400 m/s. High-velocity rifle cartridges can exceed 900 m/s.

Can I use joules and grams instead?

Yes. Convert grains to grams (multiply by 0.0648) and ft·lb to joules (multiply by 1.356), then apply v = √(2KE/m).

Why is my measured velocity lower?

Air resistance, incomplete energy transfer, and measurement distance all reduce observed velocity below ideal muzzle values.

Does bullet shape affect this calculation?

This formula uses mass and energy only. Ballistic coefficient and drag affect trajectory after the bullet leaves the barrel but not the ideal muzzle speed from energy.

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