Does my arrow hit hard enough?
Kinetic energy and momentum tell you roughly how much a bow setup can push an arrow through hide and bone. Enter your total arrow weight and its speed for the numbers and the game class they suit - then remember that a sharp broadhead in the right spot beats raw energy every time.
Kinetic energy is a rough guide to penetration potential across game sizes.
How this works
- Kinetic energy = arrow weight (grains) × speed² (fps) ÷ 450,436, in foot-pounds. The divisor turns grains into pounds (7,000 grains to the pound) and divides by twice standard gravity (2 × 32.174 ft/s²).
- Momentum = arrow weight × speed ÷ 225,218, in slug-feet per second (7,000 × 32.174).
- The game bands are the Easton guideline as Bowhunting.com quotes it: under 25 ft-lbs small game, 25-41 deer and antelope, 42-65 elk, black bear and boar, over 65 the toughest big game.
What it leaves out:arrow flight, broadhead type and sharpness, front-of-centre balance and, above all, where the arrow hits. Energy bands are a guideline, not a legal minimum - your state may set its own draw-weight rules.
Sources: Bowhunting.com, Understanding kinetic energy (Easton guideline) · Wikipedia, Grain (unit)
These are guidelines, not guarantees. Kinetic energy figures give a ballpark for the game a setup can handle, but arrow flight, broadhead choice and sharpness, front-of-centre balance and above all shot placement matter more than any single number. Heavier arrows carry momentum and penetrate better at a given energy, and many bowhunters weight toward momentum for big game. Check your local minimum draw-weight and equipment laws, practise to your effective range, and only take broadside or quartering-away shots inside it.
Shooting a rifle for the same game? See the cartridge & energy guide.
Gear for measuring your arrow setup
Links go to Amazon or a partner store (such as OpticsPlanet) and may earn us a commission at no extra cost to you. As an Amazon Associate we earn from qualifying purchases. We link gear types, not sponsors' picks: you choose the exact product.