FPS Calculator / Joule Calculator

How to Use

Use the above calculators to make sure your gun is within the necessary energy / fps limits set forth by your local airsoft field or any milsim you are planning to attend.

The top "Joule Calculator" will allow you to calculate the energy your gun will shoot if you've measured your FPS and know the ammunition (bb weight) that was used during the chrono.  This will allow you to ensure your gun is within the energy limit. 

The bottom "FPS Calculator" will allow you to calculate the FPS of your gun if you've measured your energy and know the ammunition (bb weight) that you plan to use.  This will allow you to estimate the FPS of your gun using certain ammunition to ensure your gun is within the FPS limit.

BEWARE OF JOULE CREEP

All guns - though especially gas guns and HPA guns - experience joule creep.  It is important to always chrono your gun with the bb you plan to use, and calculate the joules from there.  You cannot simply take the joule output value on the top calculator, input it into the FPS calculator on the bottom, and assume that your gun will be legal.  While it is a useful estimation, different weight bbs may affect the amount of energy your gun can output, especially if they are gas or HPA.

TYPICAL ENERGY LIMITS

Most outdoor fields and engagements allow up to 1.75J, with sniper rifles allowed higher energy with minimum engagement distances (MED).  Anything above 1.75J at close range will typically bruise and break skin.  Some fields go up to 2J and enforce strict MED for all players.

Most indoor fields and engagements allow up to 1.25J with no MED.  Guns under 1J will sting at close quarters, but will typically not cause skin to break or bleed.

Different fields and ops have different rules.

Be safe!  Have fun!  And always obey local field regulations.