Bow Hunting Kinetic Energy Calculator
Calculate arrow kinetic energy and momentum for bow hunting.
Enter arrow weight and speed to check if your setup meets minimum standards for ethical harvests.
Arrow Kinetic Energy Formula
KE (ft-lbs) = (Arrow Weight in grains × Arrow Speed in fps²) / 450,240
The constant 450,240 converts grains and fps into foot-pounds.
Arrow Momentum: Momentum (slug-fps) = (Weight in grains × Speed in fps) / 225,400
Momentum is preferred by many hunters for penetration on heavy game — it decays more slowly than KE as the arrow slows inside tissue.
Minimum kinetic energy guidelines (general):
| Game | Minimum KE |
|---|---|
| Small game (rabbit, turkey) | 25 ft-lbs |
| Whitetail deer | 40 ft-lbs |
| Elk, black bear | 65 ft-lbs |
| Moose, grizzly bear | 80+ ft-lbs |
Optimal arrow weight: 6-8 grains per pound of draw weight (GPP). Heavier arrows retain energy better, fly quieter, and penetrate deeper. Lighter arrows fly faster but lose energy faster and can be deflected by brush.
Check your bow manufacturer’s arrow weight minimum — too light can damage the bow.