This Airsoft FPS Calculator calculates both the fps (Feet per second) based on the Joules and BB weight, or the Joules based on the BB weight and the velocity.
The law is different depending on the firing modes of the airsoft gun. For example, the joule limit for a fully auto airsoft gun is 1.3J. The limit for a DMR or Bolt Action Sniper Rifle (Single Shot or Semi Only) is 2.5J

Remember we have strict velocity rules in the UK, at the bottom of the calculator, you will see if your airsoft gun is within UK legal limits. Please use this Airsoft FPS calculator and keep airsoft safe in the UK.
Airsoft Safety Rules
Legal Compliance
- Legal Limits: Use the provided calculator to ensure your airsoft gun is firing within UK legal limits.
Safe Area Rules
- Barrel Sock in Safe Area: Always use a barrel sock when in the safe area to prevent accidental discharge.
- Safe Area Etiquette: Safe areas are designated as such for a reason. Always observe the rules to maintain safety.
- Battery and Barrel Sock: Attach the barrel sock before connecting the battery to your airsoft gun.
- Battery Removal: Keep the barrel sock on until the battery is removed from your gun. This rule applies only within the safe area.
- Barrel Sock Outside Safe Area: Outside the safe area, barrel socks can safely be removed.
Personal Protective Equipment (PPE)
- Sealed Eye Protection: All eye protection must be sealed to your face. Glasses are not suitable unless they have rubber seals and an elastic strap that goes around your head.
Pyrotechnics
- CE-Approved Pyro: All pyrotechnics must be CE approved to be legal in the UK. If your pyro does not have a CE mark, it is not legal for use.
- Smoke Grenades: These should also be CE approved and should not be used during very dry conditions to prevent fire hazards.
Play safe, take your hits and have fun.
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