1. What is Foot Pounds of Energy?

Definition: Foot pounds of energy (ft-lb) is a unit of measurement for the kinetic energy of a projectile.

Purpose: It helps hunters, shooters, and ballisticians evaluate the stopping power and effectiveness of ammunition.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( E \) — Energy in foot-pounds (ft-lb)
• \( m \) — Projectile mass in grains
• \( v \) — Projectile velocity in feet per second (ft/s)
• 450240 — Conversion factor (2 × 7000 grains/lb × 32.174 ft/s²)

Explanation: The formula calculates kinetic energy by taking half the mass times velocity squared, with appropriate unit conversions.

3. Importance of Energy Calculation

Details: Knowing the energy helps determine ammunition effectiveness for hunting different game, penetration capability, and recoil estimation.

4. Using the Calculator

Tips: Enter the projectile mass in grains (1 grain = 1/7000 lb) and velocity in ft/s (typically from chronograph measurements). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is mass measured in grains?
A: Grains are the standard unit for measuring bullet and powder weights in ballistics (1 grain = 64.79891 milligrams).

Q2: What's a typical energy range for hunting?
A: Small game: 200-500 ft-lb, medium game: 1000-2000 ft-lb, large game: 2000+ ft-lb.

Q3: Where does the 450240 constant come from?
A: It's derived from unit conversions: 2 × 7000 grains/lb × 32.174 ft/s² (acceleration due to gravity).

Q4: How accurate is this calculation?
A: It provides theoretical maximum energy. Real-world energy may be slightly less due to factors like air resistance.

Q5: Can I use this for arrows?
A: Yes, but arrow mass is typically measured in grains already, and velocity in ft/s.