/ Airsoft FPS & Joules Calculator
Input your details into our handy calculator to convert your airsoft gun's velocity in Feet Per Second or Meters Per Second between different weights of BB
Step 1:
Enter the Velocity from your chronograph
Step 2:
Enter the BB Weight that you used to chronograph
Step 3:
Done, you can now read the estimated velocity on a 0.20g BB below
Airsoft FPS & Joules Calculator
Input Data
Converted Results
These values are estimates based on energy conservation. Actual velocity may vary due to joule creep and other factors. Always verify with a chronograph before gameplay.
Understanding Airsoft FPS & Joules
To help you stay within your site's FPS limit, this tool is preset to convert an FPS reading from firing with a 0.25g BB to the equivalent FPS for a 0.20g BB. The input and output BB weights can be adjusted according to your needs, and the energy value (not essential) may also be entered if known to skip a step.
The resulting velocities are only ever estimates as there are other factors to take into account when calculating a velocity that are far too complicated to calculate effectively (the phenomenon known in the industry as joule creep).
The physics behind this calculator involves the principle of energy conservation. When you fire a BB, the energy transferred to it remains constant regardless of the BB's weight. However, heavier BBs move slower while carrying the same energy.
This calculator uses the formula E = ½mv² where E is energy in joules, m is mass in kilograms, and v is velocity in meters per second. By calculating the energy from your known FPS and BB weight, we can then determine what the velocity would be with a different BB weight.
Common UK Airsoft Site FPS Limits
| Weapon Type | FPS Limit (0.20g) | FPS Limit (0.25g) | Joules | Minimum Engagement Distance |
|---|---|---|---|---|
| AEG/GBB (Full Auto Capable) | 350 FPS | 328 FPS | 1.14 J | None |
| DMR (Semi-Auto Only) | 450 FPS | 421 FPS | 1.88 J | 20-30m |
| Bolt Action Sniper | 500 FPS | 467 FPS | 2.32 J | 30-40m |
Note: Limits may vary between sites. Always check with your local site for their specific rules and regulations.
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