Energy at Impact Calculator
Calculate remaining kinetic energy and velocity at any distance from bullet weight, muzzle velocity, and ballistic coefficient.
About this calculator
A bullet's kinetic energy — the number that ultimately determines its terminal effect on a target — is computed from the standard grains/fps-to-foot-pounds formula, KE = (weight x velocity^2) / 450240, where 450,240 converts grain-mass and feet-per-second units into foot-pounds. Because velocity is squared, energy is far more sensitive to velocity than to bullet weight: doubling velocity quadruples energy, while doubling weight only doubles it. This calculator first estimates how much velocity a bullet retains at your specified range, using a simplified exponential decay model driven by the ballistic coefficient (BC) — a single number summarizing how well a bullet resists aerodynamic drag, where a higher BC (closer to 1.0) means a more streamlined bullet that sheds velocity more slowly downrange.
Muzzle energy, computed at zero range, depends only on bullet weight and muzzle velocity — it doesn't involve the drag model at all, since there's no distance for drag to act over yet. Energy and velocity retention percentages express how much of the muzzle values survive to the target range, useful for comparing loads independent of their absolute muzzle numbers. What this tool does not account for: the true multi-term drag curve (G1/G7 drag functions) that professional ballistic software uses instead of this simplified exponential approximation, altitude or temperature effects on air density and therefore drag, or bullet stability and yaw, which real-world terminal ballistics also depend on.
Inputs
Results
Energy at Impact
1,767 ft-lbs
How to Use This Calculator
- Enter Muzzle Velocity, Ballistic Coefficient (G1), and Bullet Weight.
- Set Range.
- Review the Energy at Impact (ft-lbs) result.
- Use Muzzle Energy (ft-lbs) and Velocity at Impact (fps) to inform your decision.
- Use the chart to visualize the results and explore different scenarios by adjusting inputs.
How the result changes with Muzzle Velocity
| Muzzle Velocity | Energy at Impact |
|---|---|
| 1,375 | 442 ft-lbs |
| 2,063 | 995 ft-lbs |
| 4,125 | 3,977 ft-lbs |
| 5,000 | 5,843 ft-lbs |
What each input means
- Muzzle Velocity
- Bullet speed at the muzzle.
- Ballistic Coefficient (G1)
- G1 ballistic coefficient.
- Bullet Weight
- Bullet weight in grains.
- Range
- Distance to target.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersMuzzle Velocity = 2750, Ballistic Coefficient (G1) = 0.45, Bullet Weight = 168, Range = 300 = 4 input(s) provided
- Calculate Energy at ImpactEnergy at Impact1767 = 1767
- Calculate Muzzle EnergyMuzzle Energy2822 = 2822
- Calculate Velocity at ImpactVelocity at Impact2176 = 2176
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why does muzzle energy not change when I adjust the ballistic coefficient?
Muzzle energy is computed at zero range, straight from bullet weight and muzzle velocity — the formula (weight x velocity^2) / 450240 has no distance term, so there's no drag for the ballistic coefficient to act on yet. Ballistic coefficient only affects how much velocity, and therefore energy, is lost as the bullet travels downrange to your specified impact distance.
Why does energy fall off so much faster than velocity as range increases?
Kinetic energy scales with the square of velocity, so a given percentage drop in velocity produces a much larger percentage drop in energy — losing 20% of velocity to drag means losing roughly 36% of energy, not 20%. That's why energy retention percentages in this calculator are consistently lower than velocity retention percentages at the same range.
How much does a higher ballistic coefficient actually help at long range?
A higher ballistic coefficient means the bullet decelerates more slowly, so it retains more velocity — and therefore more energy — at any given downrange distance. The benefit compounds with range: the gap between a high-BC and low-BC bullet's remaining energy is small at short range and grows substantially larger the farther the bullet has to travel, which is why long-range shooters prioritize high-BC projectiles.
Is the Taylor KO factor here the same as the official Taylor Knock-Out formula?
This calculator's Taylor KO figure is a simplified version — the original Taylor Knock-Out formula multiplies bullet weight, velocity, and caliber (bullet diameter) together and divides by 7000, but this calculator omits the caliber term since it isn't one of the collected inputs. Treat the result as a rough relative comparison between loads of similar caliber, not a caliber-independent measure of stopping power.
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