29.1 ft-lb
Your arrowScale to 90 ft-lb
Momentum0.324 slug-ft/s
Arrow weight405 gr
Arrow energy calculator
Kinetic energy and momentum tell you what your arrow carries downrange, and which game it’s suited for. Set your arrow weight and speed to see kinetic energy and momentum, and where your setup lands on the game chart.
How to use it: Tap a preset or set your arrow weight and speed, then read your energy and momentum on the right and where they land on the game bar.
// The calculator
// The math
How it’s calculated
Kinetic energy (ft-lb) = arrow weight in grains × speed in fps² ÷ 450,240. Momentum (slug-ft/s) = grains × fps ÷ 225,120.
The game classes follow Easton’s hunting guide: under 25 ft-lb small game, 25–42 deer and antelope, 42–65 elk, black bear and boar, over 65 the toughest game.
A worked example
A 405 gr arrow at 180 fps: 405 × 180² ÷ 450,240 = 29.1 ft-lb, with 0.324 slug-ft/s of momentum. That’s the deer and antelope class.
The full explanation: Crossbow ballistics: speed, energy and drop.
// FAQ
Questions about arrow energy
Quick answers about kinetic energy, momentum and what game they suit.
Energy or momentum, which matters more?
Both. Energy says how hard the arrow hits; momentum says how well it keeps pushing through. Heavier arrows win on momentum.
Is enough energy enough to hunt?
No. Energy isn’t permission. Run the ethical shot checker before every shot.
How do I raise my numbers?
More draw weight raises speed. A heavier arrow raises momentum and quiets the bow. Change one thing at a time.
// More tools
