Kinetic energy and momentum calculator
Enter your finished arrow weight and its speed and this returns kinetic energy and momentum, the two numbers that describe how hard an arrow hits. Check the result against the game you hunt in the table below. The broadheads and hunting-arrows guides carry the rest of the penetration picture.
The finished arrow: shaft, point, insert, nock, and fletching.
The measured speed off your bow, from a chronograph or your bow shop.
Enter a weight (150 to 1200 grains) and a speed (100 to 450 fps) to see kinetic energy and momentum.
Kinetic energy by game class
| Small game (rabbits, birds) | 25 ft-lbs |
|---|---|
| Medium game (deer, antelope) | 25 to 41 ft-lbs |
| Large game (elk, black bear, wild boar) | 42 to 65 ft-lbs |
| Toughest game (cape buffalo, grizzly) | 65 ft-lbs and up |
About these formulas
Kinetic energy in foot-pounds is arrow weight in grains times speed in feet per second squared, divided by 450,240. Momentum is arrow weight in grains times speed, divided by 225,400. Both are the standard archery formulas published by Easton Archery. The game-class minimums above are Easton Archery's published kinetic-energy recommendations; kinetic energy is one factor in penetration, not the whole of it.
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