Airgun Ballistics Calculator (Joules & ft/lbs)
Calculate muzzle energy for high-power air rifles. Supports .177, .22, and .25 calibers with inputs in grains or grams. Includes legal power warnings.
Projectile
About
For air rifle hunters and target shooters, understanding ballistics is critical for both accuracy and legal compliance. Unlike airsoft, air rifles often fire lead pellets measured in grains at velocities that can exceed the speed of sound. This calculator computes the Muzzle Energy in both Joules and Foot-Pounds (ft/lbs), which are the standard units for defining legal ownership limits in countries like the UK, Germany, and Canada.
Accurate energy calculation requires precise input of projectile mass. A standard .22 pellet might weigh 14.3 grains, while a heavy slug could weigh 25 grains. Small deviations in weight significantly alter the calculated energy, which is strictly regulated. This tool handles unit conversions automatically, allowing shooters to input data directly from their ammo tins.
Formulas
The calculator uses the kinetic energy formula, adapted for imperial units often used in ballistics (grains and feet per second):
The constant 450240 is derived from 2 × 32.174 (gravity) × 7000 (grains per pound). For metric inputs, the standard SI formula is used:
Reference Data
| Region | License Limit | Equiv. Energy | Typical Metric |
|---|---|---|---|
| United Kingdom | 12 ft/lbs | ~16.27 J | FAC required above |
| Germany | 7.5 J | ~5.53 ft/lbs | F-stamp req. |
| Canada | 500 FPS & 5.7 J | Both conditions | PAL required above |
| USA | None (Federal) | N/A | Varies by State |