December 30, 2021

What Does FPS Mean In Airsoft?

Firstly - let's make sure we don't confuse FPS in airsoft with other meanings of the abbreviation 'FPS'.

In airsoft, FPS means 'feet per second' and is a measurement of velocity (speed). It's pretty much ubiquitous and the core measurement that manufacturers and airsoft fields use to determine how much power an airsoft gun has on a standardised airsoft pellet weight.

Regardless of what type of gun you buy, you'll find its FPS marked to denote the muzzle velocity of the gun.

How is FPS calculated in airsoft?

FPS is calculated by using chronographs in airsoft.

These devices measure how long it takes the BB pellet to travel from point A to point B; this is usually a short distance contained inside the chronograph. They work on the same principle as the radar guns that the police use to determine how fast a vehicle is moving.

Measuring the FPS of a BB pellet is the main way that airsoft sites regulate the guns that airsoft players bring to their playing site to ensure they are not too powerful. 

By measuring the amount of time it takes for the pellet to travel this distance they can record the speed of the pellet (also known as the velocity of the pellet).

Once we know the weight of the BB pellet used and the speed that the pellet was travelling we can work out the kinetic energy of the pellet. This is important as there is a legal limit that stipulates the maximum kinetic energy that an airsoft gun can possess. 

Why are there FPS limits in airsoft?

All airsoft sites in the UK regardless of if they are an indoor field or an outdoor field will have an FPS limit. These field limits are set by the sites to improve gameplay, reduce the chance of injury, and ensure that no laws are broken.

Quite often these limits will also be imposed by the insurance companies that cover these sites. 

These limits usually tie in with the legal limits written into UK law. The legal limits are based on the kinetic energy of the weapons.

  • The limit is 1.3J for automatic weapons (that can fire multiple projectiles from one trigger pull)
  • 2.5J for single-shot weapons (where only one projectile is fired regardless of how long the trigger is held down). 

The good thing about having limits set means that the manufacturers of protective gear such as ballistic glasses and face masks have a set figure that their equipment must be rated above; helping to ensure everyone's safety whilst participating in the sport.

Because there is a correlation between FPS, BB weight, and energy it also means there is a maximum velocity that a BB can travel at before it is over the limit.

This makes it possible to quickly establish if an airsoft rifle or pistol is above or below the legal limit by using a chronograph to measure the FPS. 

Is it illegal to have high FPS guns?

Yes and no.

Whilst there isn't an FPS limit defined by law, if your FPS is above a certain velocity for a given weight it will have a kinetic energy value (in joules) greater than the allowed limits.

Whilst these limits are slightly above the limits set by most UK airsoft sites, the only time you would be able to use them would be on private property that you either owned or had permission to use.

Below shows the common FPS limits on different BB pellet weights in order to stay under the Joule limits of UK law:


Max FPS and joules for auto

Max FPS for semi-auto

England and Wales

374fps with 0.20g BBs (1.3J)

518fps with 0.20g BBs (2.5J)


374fps with 0.20g BBs (1.3J)

518fps with 0.20g BBs (2.5J)

Northern Ireland

328fps with 0.20g BBS (1.0J)

328fps with 0.20g BBs (1.0J)

If your weapon allows for automatic firing then as soon as your weapon is above these limits it is immediately deemed illegal and classed as an actual firearm.

If you are found to be in possession of what is classed as a 'Section 5' firearm then you could be facing at least 5 years in prison. If your weapon is semi-automatic or bolt-action then this type of gun becomes classed as an air-gun which is very likely to be illegal to be used at an airsoft field as you would be firing at other people.

What is the best FPS for airsoft guns?

This question is subjective - whilst most players will strive for the highest FPS then can achieve it is always important to remember that higher FPS does not always equal increased range (more on that later).

Nearly all Tokyo Marui airsoft rifles come out of the box at 270-280 FPS; a whopping 70 FPS less than the UK limit for automatic airsoft guns yet these are regarded to outperform a lot of other manufacturers that come out of the box shooting 350 FPS. 

The most common FPS range for automatic electric guns or automatic gas-powered guns is 300-350 FPS. At the top of this range, the velocity of your pellet is travelling at the equivalent of 238 Miles Per Hour. 

Players who use marksman rifles tend to use weapons at the 400 FPS mark, and players that use spring-powered airsoft guns such as a sniper rifle are normally at the maximum muzzle velocity allowed by UK sites; 500 FPS.

Whilst these players have an advantage in that their FPS is higher and therefore their pellet velocity is greater they also normally have a minimum engagement distance that they are allowed to shoot players from.

If they have a target within this distance they are forced to switch to a secondary weapon, forcing them to adopt more realistic military tactics when it comes to choosing targets and changing weapons.

To further investigate what the best FPS is for a gun you need to consider its use case. I

f you tend to play primarily on indoor fields or close-quarters battles then the extra velocity afforded by a lighter pellet and increased FPS could be the difference between winning and losing a firefight.

On the other hand, if you are playing on an outdoor field it may be better to use a heavier weight pellet to increase your effective range and accuracy with the trade-off of it taking longer for the pellet to reach the target.

Does the FPS of a gun increase range?

This is also a yes and no question.

Whilst FPS does not directly give you extra range it does have an impact on how well your BB can retain its actual energy, a byproduct of which is an increase in effective range.

As mentioned earlier Tokyo Marui rifles tend to be classed as medium power guns as they have a reduced FPS to comply with stricter Japanese laws, but they can still out-range a lot of other manufacturers. Having said that one of the first upgrades most players undertake is an upgraded spring, showing that the FPS and power of a gun are still at the forefront of their minds when preparing for upcoming airsoft battles.

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