SOCOM’s Airsoft FPS Chart, Calculator & Expert Advice

Airsoft FPS Calculator

FPS is an important measurement, but calculating the Feet Per Second of your weapon can be a bit confusing – especially if you don’t know where to start. Our airsoft FPS chart and calculator make that a whole lot easier. 

There’s no denying that a decent rate of fire and force of impact can be the difference between victory and defeat, so it’s essential to know exactly how fast you’re firing during a skirmish.

Calculating your joules from FPS can get a bit confusing, but at Socom Tactical, we’ve got you covered. Our FPS to Joule Calculator can help you get the highest FPS for your airsoft guns. So, let’s get into it!

Airsoft FPS Chart

Airsoft FPS Chart
SOCOM's Airsoft FPS Chart, Calculator & Expert Advice

Credit: Novritsch

Airsoft FPS Helpful Tips

what is airsoft FPS
SOCOM's Airsoft FPS Chart, Calculator & Expert Advice

If you’re new to the world of airsoft, understanding the FPS and joules of your gun can be confusing. 

Our airsoft experts have put together some helpful tips to help you understand more about FPS and how it affects the performance and quality of your airsoft weapon.

The Impact of BB Weight

The weight of your BB pellets will have an effect on the way your gun fires and the force of the impact. Some players prefer to stick to the lighter BBs no matter what.

Lighter BBs mean a higher FPS because less energy is required to propel them through the air. Heavier BBs require more energy to travel through the air, so their FPS is naturally lower.

What is MPS?

You may have encountered airsoft weapons that reference MPS instead of FPS. In countries that use the Metric System, muzzle velocity is measured in Metres Per Second (MPS) rather than feet, but it essentially represents the same concept. 

When it comes to imported airsoft guns, you are more likely to come across MPS rather than FPS, especially when compared to UK-made guns.

As a general rule, 1FPS = 0.3048MPS.

What About Kinetic Energy?

An additional valuable metric to assess the firing quality of an airsoft gun is the amount of kinetic energy it transfers to the target. Essentially, this means how hard your BB pellets hit the target.In airsoft, the name of the game isn’t to actually hurt anyone.

With that said, the impact needs to be strong enough for the target to register the hit regardless of the tactical gear they may be wearing.#

Determining Your Optimum FPS Rate

There are multiple factors that determine or influence what your ideal or optimum FPS rate is. 

  • BB weight
  • The power of your gun
  • Joule rating

BB weight is the biggest variable that affects the FPS of your weapon. Of course, FPS is also affected by the power generated by your gun’s firing mechanism as well as the FPS limit imposed by the manufacturer.

But FPS is only half of the story when it comes to the power of your airsoft gun. Equally important is the joule rating – a unit of energy that measures the amount of work required to move an object. 

Joules is an important measure for UK airsofters to not only understand how powerful their gun is but also to make sure they’re within safe site limits. 

Airsoft Power Limitations in the UK

Airsoft sites across the country differ in what is an acceptable FPS, and site limits should always remain under the legal recommendations.

The energy expended when firing your airsoft gun determines whether, in the eyes of the law, your airsoft gun is considered a dangerous firearm. The Policing & Crime Act introduced an exception for airsoft guns, not classifying them as firearms so long as they meet certain measures regarding ammunition laid out in the Firearms Act.

Airsoft guns, whether fully automatic with 1.3 joules or less or single-shot (or semi-automatic) with 2.5 joules or less, do not meet the lethality threshold defined by the Firearms Act.

They are not classified as firearms as long as they are designed to fire plastic BB pellets that are no larger than 8mm, and their muzzle energy does not exceed 1.3 joules for successive shooting capabilities or 2.5 joules for individual shooting capabilities.

So, 1.3 joules for auto-fire or burst-fire airsoft guns and 2.5 joules for single-shot or semi-auto airsoft guns.

How to Calculate Impact

When customising your airsoft gun or considering using heavier BB pellets, it’s crucial to ensure that you stay within acceptable FPS limits. Remember, FPS is relative to the weight of the BB you use, but the resulting kinetic energy remains constant.

An example is if your airsoft gun shoots at 400 FPS when loaded with a 0.2g BB pellet; this will reduce to 270 FPS when using a 0.45g BB pellet. This is a significant difference in FPS, but the kinetic energy produced during flight will remain constant at 1.52 Joules, regardless of the weight of the BB pellet you use.

If you’re still not sure, you can use an airsoft FPS calculator to work out how your weapon will be affected by different BB weights.

The Golden Formula

This is where it can get confusing. To calculate kinetic energy in Joules, you must use this formula:

J = 0.5 x m x v2 Joules (J) = 0.5 x the mass (m) of the bb (kg) x the speed squared (v2)

Check Your Gun With Our Airsoft FPS/Energy Calculator

To help you figure out this confusing but essential aspect of airsoft gun quality, we’ve created this handy chart. Just line up your current FPS with the BBs you plan to use.

Check your FPS Limit

Change the values below and click CHECK to see your results.

Weight of BB (g):

Your Kinetic Energy (in Joules):


How Does the Weight of BBs Affect FPS?

Lighter BBs have a higher FPS because less energy is required to propel them through the air. On the other hand, heavier BBs require more energy to travel through the air; hence, their FPS is naturally lower.

What is a Joule Rating, and Why is it Important in Airsoft?

A joule is a unit of energy that measures the amount of work required to move an object. In the context of airsoft, it helps you understand how powerful your gun is and whether it’s within safe site limits. In the UK, airsoft guns are expected to fire at around 1.3 joules.

How are Airsoft Guns Classified in the UK?

Airsoft guns are not classified as firearms if their muzzle energy does not exceed 1.3 joules for auto or burst-fire airsoft guns or 2.5 joules for single or semi-auto airsoft guns and if they are specifically designed to discharge BB pellets that are 8mm or smaller in size.

How Can I Calculate the Impact of My Airsoft Gun When Using Different BB Weights?

To calculate the impact with different BB weights, you can use the kinetic energy formula mentioned above, adjusting the mass and velocity based on the new BB weight. Of course, you can also use our handy airsoft energy calculator to make it a bit easier!

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