Choosing the right size 4500 psi carbon fiber tank comes down to one question: how much air do you need between refills? A tank that is too small means constant trips to the compressor; one that is too big means carrying weight you never use. This guide walks through the full 0.36L to 12L range so you can match the cylinder to your air rifle, paintball marker, or dive setup.
Tank sizes at a glance
Carbon fiber cylinders are sold by internal water volume in liters, sometimes with the cubic-inch equivalent in parentheses. The most common 4500 psi (310 bar) sizes are:
- 0.36L (22 cu in) – ultra-compact; a buddy bottle or tank-mounted air source for short sessions.
- 0.5L (30 cu in) – compact; handy for quick PCP top-ups and airsoft use.
- 1.1L (67 cu in) – portable; a popular mid-size for air rifles that stays light in a backpack.
- 2L-3L – versatile; covers longer shooting sessions without going back for a refill.
- 4.7L-6.8L (287-415 cu in) – the sweet spot; the 6.8L 68/4500 is the best-selling all-round size.
- 9L (550 cu in) – high capacity; refills smaller tanks and covers long paintball or dive days.
- 12L – maximum; built for firefighting, rescue, and heavy-duty professional use.
Because carbon fiber is far lighter than steel, even a 6.8L cylinder stays easy to carry – a comparable steel tank would weigh roughly twice as much for the same air.
For PCP air rifles: match the tank to your fill habit
Your pcp air tank is really a portable air reservoir. Smaller 0.36L-1.1L bottles are light enough to shoot with directly or carry in a backpack, giving you several refills for a typical PCP rifle before you need the compressor again. If you shoot all afternoon, a 4.7L or 6.8L cylinder holds several times more air, so one tank covers the whole session. Think about how far you are from your fill source: the farther the walk or drive, the bigger the tank you want.
For paintball: 68/4500 is the standard for a reason
Walk onto any serious paintball field and most HPA setups run a 68/4500 hpa tank – 6.8 liters at 4500 psi. It is the default because it balances air capacity, weight, and size for a full day of play. Smaller 0.36L-1.1L tanks work as lightweight setups for speedball, while a 9L tank is heavy to carry but excellent as a fill-station tank at the staging area.
For scuba and diving: go bigger, stay light
Divers switching to a carbon fiber scuba tank usually pick 6.8L-12L. A 6.8L 300 bar cylinder gives serious bottom time at a fraction of a steel tank’s weight, and 9L-12L sizes suit technical dives or buddy teams sharing air. Remember that 4500 psi equals 310 bar, so any 4500 psi carbon fiber tank is a true 300 bar scuba tank – just confirm your regulator and valve are rated for that pressure.
Weight, valves, and filling
Every size up adds air but also length and a little weight. Before you buy, check three things: first, the valve thread matches your fill station or regulator; second, you have a way to fill to 4500 psi – a 300 bar compressor, a hand pump, or a dive shop; third, the tank carries the certification you need (DOT for the United States, CE for Europe). A pcp air tank with fill station valve lets you refill air guns and smaller bottles directly from the big tank, which is why many shooters pair a 6.8L or 9L cylinder with a fill station.
Quick recommendations
- Backyard plinking and short sessions: 0.36L-1.1L
- All-round PCP shooting and paintball: 6.8L (68/4500)
- Fill station and team use: 9L
- Diving, firefighting, and rescue: 6.8L-12L
When in doubt, the 6.8L 4500 psi carbon fiber tank is the size most buyers end up happiest with – big enough for a full day, light enough to carry. Browse the full range in our carbon fiber cylinder collection.