CQC Ballistics System Online

FPS & Joules
Calculator

Convert airsoft muzzle velocity between FPS and Joules using your BB weight. Use the comparison chart to better understand how BB weight affects velocity while muzzle energy remains the same.

Input Parameters

Ballistic Data

Calculator Ready
FPS
GRAMS
Calculated Output

Energy Analysis

Live Reading
Calculated Muzzle Energy
1.49 Joules
400 FPS using a 0.20g BB produces approximately 1.49 Joules.
Velocity
400.0 FPS
Metric Velocity
121.9 M/S
BB Weight
0.20 GRAMS
Muzzle Energy
1.49 JOULES
Energy Output Indicator
Moderate Energy

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.

01

Chronograph Correctly

Use the BB weight selected on your chronograph or enter the actual BB weight into this calculator.

02

Watch for Joule Creep

Some airsoft guns can produce higher energy with heavier BBs, especially HPA, gas and long-barrel platforms.

03

Confirm Field Limits

Always check the rules and minimum engagement distances at the field where you intend to play.

Calculation Formula J = ½ × mass in kg × velocity in m/s²
Important: This calculator provides mathematical estimates for general airsoft reference. Chronograph calibration, BB tolerances, hop-up settings, air pressure, temperature and other factors can affect real-world readings. This tool does not determine whether an airsoft gun is legal or permitted at a particular field. Always confirm current field rules, local regulations and equipment requirements before use.