Two of the most asked questions from new paintball players are, what is the difference between CO2 and compressed air and what is better, CO2 or compressed air? CO2 and compressed air (HPA) are both high pressure gas sources that are required on most paintball guns.

Depending on your paintball gun, sometimes only one kind can be used without causing damage!

When paintball first started all paintball guns, used CO2 as their gas source. CO2 was the standard for many years. When CO2 is stored in a bottle it is in liquid form, and needs to expand into gas for it to work correctly with paintball guns. When the liquid CO2 expands into gaseous form it creates pressure; this pressure is what fires the paintball.

CO’s biggest problem is the expansion from liquid to gas. As the liquid CO2 expands it cools, this chilling also slows down the rate of expansion resulting in a loss of pressure. In order for the CO2 to expand correctly it needs to be warm, around 75°F (23°C). This drop in pressure will cause the guns velocity to fluctuate more so than it would with compressed air. So the faster it expands, the colder it gets. In other words the faster the gun is fired the the colder it will get. This is fine when used on mechanical style guns in the summer, but electronic guns that have a higher rate of fire will suffer more from the drop in pressure.

CO2 tanks do however have some advantage. The main reason people end up going with CO2 is that it has a considerably lower initial cost. The 20oz CO2 tank is the most popular size, it is sold for around $22 and can shoot 1000+ paintballs. The amount of shots/cost is a great way for players that play on private property to play a lot of paintball for little cost. You could pick up a handful of CO2 tanks and play all day. Refills can cost anywhere from $3 to $7. If you don’t have a paintball shop or field near by, many welding and fire extinguisher supply shops can fill CO2 tanks.

In comes compressed air. Compressed air tanks started gaining popularity in the early 90s, when guns started to shoot faster and the drawbacks of CO2 became more apparent. Compressed air is also known as High Pressure Air (HPA), Nitro, N2 or Nitrogen Tanks. Compressed air is just what it sounds like, compressed atmosphere. Tanks come in various size, and 3000 PSI or 4500 PSI. The difference 3000 PSI and 4500 PSI is not the output pressures of the tank but rather the pressure that the tanks can hold, thus the 4500 PSI is result in more shots than the 3000 PSI.

Compressed air’s main advantage is consistency. The more consistent pressure results in much more consistent velocity and help with accuracy some. Compressed air is marginally effected by temperature, unlike CO2, making it great for cold weather. Most paintball fields charge for all-day compressed air fills. A flat rate is paid at the beginning of the day, typically $5 to $10 and you can fill your tank as many times as you like. While the initial cost is more, in the long run you could end up saving money going with compressed air.

The downside of compressed air is the initial cost. Tanks can range anywhere from $40 to $250. To get as many shots on compressed air as you would that 20oz CO2 tank, a 68 CI 4500 PSI compressed air tank is needed.

Another important note is that some guns will only work with compressed air. A general rule is that most electronic paintball guns should use compressed air, and mechanical guns can use either compressed air or CO2.