Airsoft FPS & Joules
Calculator
Use our airsoft FPS and joules calculator to convert muzzle velocity to energy—or joules to FPS—using your BB weight. The comparison chart shows equivalent velocities at a fixed muzzle energy.
Ballistic Data
Energy Analysis
This reading is commonly associated with standard outdoor airsoft configurations, but field limits vary.
Equivalent FPS by BB Weight
The table below shows the approximate FPS produced by the same calculated muzzle energy when using different BB weights.
| BB Weight | Equivalent FPS | Velocity M/S | Energy |
|---|
Understanding the Result
FPS measures projectile speed. Joules measure the total kinetic energy carried by the BB.
Chronograph Correctly
Use the BB weight selected on your chronograph or enter the actual BB weight into this calculator.
Watch for Joule Creep
Some airsoft guns can produce higher energy with heavier BBs, especially HPA, gas and long-barrel platforms.
Confirm Field Limits
Always check the rules and minimum engagement distances at the field where you intend to play.
J = ½ × mass in kg × velocity in m/s²