Free tool · PCP air rifles
PCP calculator
See how many shots you get per fill – and how many times a scuba tank can fill your rifle before it needs refilling itself. What do the terms mean?
Your rifle
Your scuba tank
Shots per fill
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- Energy per shot
- –
- Full fills from the tank
- –
- Total shots from the tank
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Guide estimate only. Regulator, valve, temperature and pellets all affect the result. "Drop-off" is the pressure at which the rifle starts shooting lower – if it is not in the manual, 100 bar is a good starting point for unregulated rifles.
How to use the calculator
A PCP (pre-charged pneumatic) air rifle has a built-in air reservoir that you fill with a pump, a scuba tank or a compressor. Every shot uses a little of the air, and once the pressure has dropped too far, the rifle needs filling again. Here are the figures you need – and where to find them.
Cylinder size (cc)
How much air the rifle's cylinder or bottle holds, measured in cubic centimetres. You will find it in the manual or the product description.
Bigger cylinder = more shots per fill.
Fill pressure (bar)
The pressure the rifle is filled to. It is shown on the rifle's pressure gauge or in the manual – typically between 200 and 250 bar.
Never fill above the pressure specified by the manufacturer.
Drop-off pressure (bar)
The pressure at which the rifle starts shooting noticeably lower and you should refill. On regulated rifles it is typically a little above the regulator setting. If you do not know it, start with 100 bar.
The bigger the gap between fill pressure and drop-off pressure, the more shots.
Pellet weight and velocity
The pellet weight is printed on the tin (e.g. 0.53 g). You measure velocity in m/s with a chronograph. Together they give the energy per shot in joules.
More energy per shot = fewer shots per fill.
What is the difference between a regulated and an unregulated rifle?
A regulated rifle has a regulator that keeps the pressure to the valve constant. This gives more consistent velocity from shot to shot and often more usable shots. An unregulated rifle shoots slightly differently as the pressure drops – which is why it matters to know the drop-off pressure.
Why does the figure not match my rifle exactly?
The calculator gives an estimate. Valve, hammer spring, regulator, temperature and pellet type all affect air consumption. Use the figure as a guide – and count your shots next time you empty a fill.
How do I fill my PCP rifle?
With a hand pump, from a scuba tank with a fill adapter, or with a high-pressure compressor. Always use the correct fill probe for your rifle, and fill slowly. If you fill from a scuba tank, the calculator shows how many fills the tank gives you.
Why does my scuba tank give fewer fills than I expected?
Once the tank pressure drops below the rifle's fill pressure, it can no longer fill the rifle completely. A 300 bar tank therefore gives more full fills than a 200 bar tank – even if the tanks are the same size.
My rifle shoots inconsistently or loses air – what now?
It may be a leaking O-ring, a worn valve or a regulator that needs adjusting. Our workshop services and repairs PCP air rifles – even if you bought yours elsewhere.
