💥 Arrow Kinetic Energy Calculator
Turn your arrow's weight and speed into kinetic energy and momentum, with Easton-style game brackets. KE is the headline hunting number; momentum reflects drive through resistance.
💥 Arrow kinetic energy & momentum
65 ft·lbf and up — the range recommended for the toughest game (cape buffalo, grizzly).
KE (ft·lbf) = (grains × fps²) ÷ 450240; momentum (slug·ft/s) = (grains × fps) ÷ 225218. KE is the headline hunting number; momentum better reflects an arrow's drive through resistance. The game brackets follow widely cited Easton bowhunting guidance and apply to hunting only — target archers need no minimum.
Energy, momentum, and honest expectations
Kinetic energy tells you how much "work" an arrow can do on impact, and it's the figure most hunting charts are built around. But because KE scales with the square of speed, two arrows with the same KE can behave very differently — the heavier one usually penetrates better, which is where momentum comes in.
Use the brackets as a reference, not a rulebook: shot placement, broadhead choice, and clean arrow flight matter as much as any number, and hunting is governed by your local regulations. For target shooting, ignore the game brackets entirely and chase consistency instead.
❓ Frequently Asked Questions
How is arrow kinetic energy calculated?
Kinetic energy in foot-pounds equals the arrow's weight in grains multiplied by the square of its speed in feet per second, divided by 450240. That constant folds in the grains-to-pounds conversion and the physics of ½mv². You need your arrow's total weight and a chronograph speed.
What's the difference between KE and momentum?
KE is the headline number quoted for bowhunting energy. Momentum — grains × fps ÷ 225218 — better reflects an arrow's ability to keep driving through resistance. A heavier arrow carries more momentum than a light one at the same KE, which is why many hunters favour arrow weight for penetration.
How much kinetic energy do I need to hunt?
Widely cited Easton guidance suggests under 25 ft·lbf for small game, about 25–41 ft·lbf for medium game like deer and antelope, roughly 42–64 ft·lbf for large game such as elk and boar, and 65 ft·lbf and up for the toughest game. Always follow your local regulations and ethical shot placement.
Does target archery need a minimum KE?
No. Kinetic-energy thresholds are a bowhunting concept about ensuring a clean, ethical kill. For target and field archery, arrow speed, spine, and consistency matter far more than raw energy.
How do I find my arrow speed?
Shoot through a chronograph, or start from the bow's IBO/ATA rating and adjust down for your real draw length, draw weight, and total arrow weight. Enter your measured or estimated speed and the finished arrow weight to get KE and momentum.