Airgun Calculator  Converters and PCP Fills
This online airgun calculator will help you convert units and help you to calculate things like power and speed. It’s a joules calculator, an airgun power calculator, an fpe to joule converter and much more! And as a bonus, we’ve added a PCP fill calculator too. Read more
Energy in joules (J)
Energy in joules (J)
Energy in fpe(ft.lb)
fpe ↔ joule
joules (J) → m/s
fpe(ft.lb) → fps
fps ↔ m/s
yards ↔ metres
mm ↔ inch
grains ↔ grammes
psi ↔ bar
PCP fill calculatorA PCP air tank is the quickest and most mobile way to fill your PCP airgun. Still, what size air tank would you need? The bigger the tank, the more fills you’ll get out of it. But the tank will be heavier and take up more space too. As with many things, the size of your PCP air tank will be a compromise between handleability and the number of fills that you actually need. The most important thing to ask yourself is: how many fills do I need as a minimum to the shooting I want to do? And after that, it’s just the question of how much extra weight and space you find acceptable for additional fills.
What our PCP fill calculator does, is simple; it tells you how many fills you can expect to get from a certain size of PCP air tank with a certain type of airgun. There are a couple of fields that have to be filled in: the capacity and maximum fill pressure of the PCP air tank are variable, which means you can choose a bigger or smaller tank. A fixed number is the air reservoir capacity of your airgun. To make it easy, we’ve made a dropdown menu with lots of makes and models to choose from, which automatically gives you the needed capacity. If your PCP airgun isn’t on the list or if you’ve used a different reservoir, you can enter the capacity manually. The only two fields that are left, are the maximum pressure of the airgun reservoir and the minimum filling pressure. This is the pressure where you see a drop in fps (and a drop in impact point). And if you’ve got a regulated airgun, it’s the minimum filling pressure equals the set pressure of the regulator. After putting in those numbers, just press the ‘CALCULATE’ button and the number of fills you get from a certain PCP air tank is neatly displayed. If you think you’ll be needing more or could do with less, just change the capacity op de PCP air tank, press ‘Calculate’ again and you end up with a new number of fills from our PCP fill calculator. 

Scuba/Divers Cylinder Capacity (litres): 


Cylinder Fill Pressure (bar): 

Airgun Cylinder Capacity: 


Airgun Fill Pressure: 
Bar  
Airgun Empty Pressure: 
Bar  
Filling Hose Type: 


Approximate number of refills = 0 
Airgun calculator
This online airgun calculator really offers all that’s needed for calculating and converting all relevant units needed for airguns (or airsoft replicas). And for the sake of clarity, we’ve categorised everything:
 Power – Use the weight of the airgun pellet and the speed that you’ve measured with a chronometer to calculate the energy in joules of the fpe in foutpound. Our joules calculator can work with both grains as grammes.
 Speed – Use the power of the airgun and the weight of the pellet to calculate the pellet speed in m/s or fps (ft/s)
 Length – Convert yards to metres or inches to millimetres and vice versa.
 Weight – How many grains will go into a gram? Use the converter and you’ll know.
 Pressure – From bar top psi and from psi to bar. It’s that simple.
Converting and calculating
Whether it’s a conversion you’re after or a calculation, we’ll save you the long tables and complicated formulas. Just fill in the information needed, press a button and you’re done. Converting metric to Imperial, Imperial to metric, it’s all possible. Or calculate power with our joules calculator, easy!
Many airgunners have added this airgun calculator to their favourites or added them to their desktop. We’d recommend you to do the same. Still, if you happen to find yourself without an internet connection, it’s good to have a bit of basic knowledge up your sleeve. For instance: you find yourself in a situation where you need to convert fpe to joules, but don’t have access to our fpe – joule calculator. Stress! Well, not when you read the information below.
fpe  joule calculator
Sometimes you need to calculate the power by adding the speed and projectile weight into the joules calculator we’ve got in our airgun calculator. Other times, you just need to convert fpe to joules. If so, this all you need to know about power (energy):
1 fpe = 1,36 joules and 1 joule = 0.74 fpe
Actually, fpe is a bit of a weird one, as it isn’t actually a unit but a quantity meaning footpoundenergy. The unit of that is footpound (ft.lb or ft.lbf, which means footpoundforce). So where in metric you ask for the energy (power) and get joules, in Imperial measurements you can get the answer: ‘It’s this much ‘energy’. A bit confusing perhaps, but there you go. All you need to know is that 1 fpe equals 1 ft.lb.
Muzzle energy calculator
Speed can be measured in both metric and Imperial units. Feet per second and metres per second are the two most used when it comes to airguns. This is how they relate to each other:
1 fps = 0.30 m/s and 1 m/s = 3.28 fps
Often, the speed we’re talking about will be the muzzle speed. This is the speed of the projectile right after it leaves the barrel. By using fps, you’ll get more refined results compared to using m/s. But whichever one of the two you choose, you’ll be able to see variations in speed more clearly and detailed than when you would when measuring in miles per hour or kilometres per hour. Still, if you’re curious:
1 mph = 1.61 km/h and 1 km/h = 0.62 mph
mm to inch  inch to mm
Millimetres and inches are used to measure the calibre. 4.5 mm for example, is 0.177 inch and 5.5 mm is 0.22 inch. This is often shortened to .177 and .22 respectively. Important to know is:
1 mm = 0.04 inch and 1 inch = 25.4 mm
In some European countries, an inch is also called a thumb. Just measure the width of your thumb and you’ll see why. It’s very close to an inch and when you’re used to the metric system, this is a pretty good rule of… you got it: thumb.
yards to metres  metres to yards
Where a kilometre is neatly divided in 1000 metres, a mile is divided into 1760 yards. Confusing? Absolutely! Good luck explaining the reasoning behind that one. Or any of the imperial sizing for that matter… Luckily, the only thing you need to know for converting is:
1 yard = 0.91 metre and 1 metre = 1.09 yards
Metres and yards are used to determine the distance to something. For instance to measure the distance to a target. A rangefinder will give you a reading in metres or yards and with that information, you can dial in your rifle scope perfectly.
grains to grams  grams to grains
With grammes and grains, the weight of a projectile is measured. And grains are used for measuring powder loads when reloading, as it’s even more exact than grammes. How much more exact? This much:
1 grain = 0.06 gram and 1 gram = 15.43 grains
A bit of useless knowledge: the unit grain is a very old one and it’s said it comes from the weight of one grain of barley.
psi to bar  bar to psi
Both bar and pounds per square inch (psi) are used as a unit for pressure. In the case or airguns, that would be air pressure. And illogical as those imperial units may be, yet again they are more refined than their metric counterpart:
1 psi = 0.07 bar and 1 bar = 14.5 psi
When talking about pressure when airguns are concerned, you have to think of the air pressure inside a PCP air tank or the pressure that’s read on the manometer of a regulator. And don’t forget, there’s pressure inside the old breakbarrel too. When airguns are concerned, it’s pressure that propels the projectile in all of them.
The complete airgun calculator
With the information above, you can calculate things yourself if needs must. But of course it’ll be a lot easier, not to mention quicker, to just use our airgun calculator. It’s all in there: a joule calculator, an airgun power calculator, a joules to pfe calculator, a muzzle energy calculator and much more. Whether you’re very serious about sport shooting, are a happy plinker in your backyard or run around an airsoft field, the airgun calculator is perfect for everybody.