Joule

Joule is a unit of energy used to measure the power of air guns and airsoft guns.

What is a Joule

Joule (symbol J) measures the kinetic energy of a projectile at the moment it leaves the barrel. The unit is named after English physicist James Prescott Joule. In the air gun and airsoft world, joule values are used for:

• Determining the power of a gun
• Comparing different models
• Setting limits at airsoft games

A higher joule value means greater penetration and a longer effective range.

How to calculate projectile energy

Projectile energy is calculated with this formula:

E = 0.5 × m × v²

Where E is energy in joules, m is projectile mass in kilograms, and v is velocity in meters per second.

Example: A pellet weighing 0.5 g (0.0005 kg) traveling at 200 m/s has energy: E = 0.5 × 0.0005 × 200² = 10 J

Air gun rules vary by country

Rules for air guns differ from country to country. Always check the legislation in your own country before ordering an air gun.

How to interpret the value

Approximate energy ranges by use:

• Under 0.5 J: Airsoft guns for indoor games
• 0.5–2 J: Outdoor airsoft, sniper roles
• Up to 7.5 J: Air rifles for target shooting, beginners
• 7.5–16 J: General-purpose air rifles, pest control
• Over 16 J: Full-power air rifles for longer distances

When choosing an air rifle, consider the intended purpose. For backyard target shooting, 7.5 J is sufficient. For pest control, choose a higher power level based on the caliber and pellet type.

Related terms: FPS, muzzle velocity, muzzle energy, caliber, air gun