CO2 vs HPA Paintball Air Tanks

Why HPA is Taking Over

HPA has steadily replaced CO2 as the go-to propellant in paintball over the past two decades, and for good reason. But CO2 still has a role. Here’s an honest breakdown from someone who’s used both extensively.

My Experience: From CO2 to HPA

I started playing paintball with a Tippmann 98 Custom and a 20 oz CO2 tank. That was the standard setup back then, and honestly, it worked fine for a while. I’d show up to the field, get my tank filled at the pro shop, and go shoot people. Simple.

The problems started when I began playing more often and in different conditions. I remember one October morning in particular — it was maybe 45°F outside, and I was playing a woodsball scenario game. First few rounds of the day, my shots were landing short. Not by a little. By a lot. Balls were arcing like they were coming out of a mortar instead of a paintball marker. By mid-game, after the tank had been sitting in the sun a bit and I’d slowed down my firing, things improved. But those first couple of games were rough.

That was my first real taste of CO2’s biggest weakness, and it bugged me enough that I started asking around. A buddy who played tournament ball told me to just get an HPA tank and stop dealing with it. So I picked up a 48/3000 aluminum tank for about $50, and the difference was immediate. Not dramatic in the way you’d notice on every single shot, but the consistency was there. My velocity stayed where I chronoed it. Cold morning, hot afternoon, rapid fire, single shots — it didn’t matter. That alone was worth the switch.

I’ve been running HPA ever since, and I’ve never once thought about going back. But that doesn’t mean CO2 is bad. It just means they’re different tools for different situations, and I want to be honest about when each one makes sense.

CO2 vs HPA: A Brief History

When paintball was first invented in the 1960s, all paintball guns used CO2. It wasn’t until the 1990s that HPA started gaining popularity as a high-upside alternative, because CO2 has a fundamental flaw built into how it works.

When CO2 is compressed, extreme pressure inside the tank (around 850 PSI or pound-force per square inch) converts it from a gas to a liquid. When you pull the trigger to fire a paintball, the CO2 in the tank undergoes a phase change from liquid back to gas. In order for this phase change to occur properly (by which we mean delivering the right amount of pressure behind your shot), the liquid CO2 needs to be around 75°F.

Here’s the problem: CO2 cools down as it expands. For every 1°F drop in temperature, the internal pressure of a CO2 tank decreases by about 11 PSI. When you’re firing shot after shot in rapid succession, that’s a lot of expansion happening in a short period of time. Your liquid CO2 gets cooler and cooler with each shot, delivering decreased pressures each time. The result? Your first few shots fly straight and hard, and then your velocity starts dropping. On a chrono, you might see your marker go from 280 FPS down to 240 FPS over a string of rapid shots. That’s a massive difference when you’re trying to hit someone behind a bunker 60 feet away.

For pump and mechanical paintball guns, which fire one shot for each trigger pull, this often is a moot point. If you’re taking a shot every few seconds, the CO2 has time to warm back up between shots, and the pressure stays relatively stable. It’s when you start shooting fast that things fall apart.

CO2 tanks are pressurized to about 850 PSI (57 atmospheres) which is right around where carbon dioxide changes from a vapor to a liquid.

Why HPA Exists: The Electronic Marker Problem

But for an electronic paintball gun with high-frequency firing modes like three-shot burst, ramping, and fully-automatic, this liquid-to-gas phase change can have a major impact. You can read more about the 5 key differences between electronic vs manual paintball guns.

Remember when I said HPA started gaining popularity in the 1990s? Not coincidentally, the first electronic paintball guns hit the market in 1996 with the WDP Angel and Smart Parts Shocker. These markers could fire 13-15 balls per second. At that rate, CO2 simply could not keep up. The cooling effect was so rapid and severe that velocity would tank (no pun intended) within seconds of holding down the trigger. Players were literally watching their paintballs lose speed mid-stream. That’s not just annoying — it makes you ineffective on the field.

This major drawback of CO2 isn’t a problem with HPA, also called Nitro or N2 because it’s simply compressed air, which is 78% nitrogen. HPA tanks are pressurized to either 3,000 PSI or 4,500 PSI, and at both of those pressures, air remains in its gaseous state. No phase change. No cooling effect. No velocity swings. You get consistent pressure as air is released with each shot, whether it’s your first shot of the day or your 500th.

HPA tanks use an onboard regulator that steps the high tank pressure down to a consistent output pressure, typically around 450-850 PSI depending on the reg. This is what gives you that shot-to-shot consistency. The regulator does the work so your marker doesn’t have to deal with pressure fluctuations.

So what’s the difference between 3,000 PSI and 4,500 PSI HPA tanks? It comes down to volume. A 4,500 PSI tank has more air compressed into the same size space, giving you more shots per fill. The 4,500 PSI tanks use carbon fiber construction (which is why they’re more expensive), while 3,000 PSI tanks are typically aluminum. Both deliver the same output pressure — you’re just getting more total air in the higher-rated tank.

The Smart Parts Shocker was one of the first electronic paintball guns, beginning the push toward HPA.

Two Advantages of CO2

Don’t write off CO2 entirely. It still has some genuine advantages.

CO2 is more affordable upfront. A typical 20 oz CO2 tank costs $20-$25 and can fire around 800-1,000 paintballs. Refills run about $3-$5 each time. Compare that to HPA tanks starting at $40 for a basic aluminum 48/3000 and going up to $200+ for a carbon fiber 68/4500. If you’re buying your first marker and trying to keep costs down, CO2 gets you on the field for less money on day one. Check out our guide to paintball costs for a full breakdown of what you’ll spend.

You can get CO2 refills almost anywhere. Welding supply shops (like Airgas), fire extinguisher shops, sporting goods stores (like Dick’s), and even some Walmart locations can fill CO2 tanks. By contrast, HPA refill options are more limited — generally just paintball fields, dive shops, or your own compressor. Standard shop compressors top out around 150 PSI, which is a far cry from the 3,000-4,500 PSI an HPA tank needs. If you live in a rural area without a paintball field nearby, CO2’s refill accessibility is a real advantage.

Four Advantages of HPA

Consistency is the biggest advantage, and it’s not close. HPA fires with the same pressure every time regardless of your firing mode, the temperature, or how many shots you’ve put through in the last 30 seconds. I can chrono my marker at 280 FPS at the start of the day and trust it’s still shooting 280 FPS four hours later. With CO2, I’d be guessing.

HPA is required for electronic paintball markers. This isn’t a suggestion — most manufacturers will void your warranty if you run CO2 through an electronic marker. The pressure fluctuations can damage solenoids and board components. If you’re playing speedball or any format where an electronic marker is the norm, HPA is your only option. CO2 effectively limits you to mechanical semi-auto markers.

HPA works with everything. Here’s the practical upside: any marker that runs CO2 can also run HPA. The reverse isn’t true. So if you buy an HPA tank now, you can use it with your current mechanical marker and your future electronic marker. It’s the more versatile investment.

HPA is easier for fields to manage. Refilling an HPA tank takes about 30 seconds — you just hook it up to a fill station. CO2 refills require liquid CO2 supply, specialized fittings, and more careful handling to avoid overfills. This is a big reason many fields are moving to HPA-only.

The Real Cost of Ownership

This is where the conversation gets interesting, because CO2’s upfront cost advantage doesn’t always hold up when you look at the full picture. Let me walk through the actual numbers.

The CO2 path: You buy a 20 oz tank for about $20. You play roughly 20 days per season (which is a pretty active recreational schedule — a couple times a month from spring through fall). Each day you need one or two refills at $4 each, so let’s call it $5 per day in CO2 costs. That’s $20 for the tank plus $100 in refills = $120 for your first season. Year two and beyond, you’re looking at about $100/year in refills, plus occasional o-ring replacements because CO2 is harder on seals.

The HPA path: A basic 48/3000 aluminum tank runs about $50. A nice 68/4500 carbon fiber tank is $150-200. Most fields charge a flat $5 fill fee per day for unlimited HPA refills. Same 20 days per season: $50 tank + $100 in fills = $150 for your first season with the cheap tank, or $250-$300 with the carbon fiber. Year two and beyond, you’re at $100/year in fill fees — same as CO2.

The break-even: If you go with the budget aluminum HPA tank, you’re paying about $30 more in year one compared to CO2, and then the costs are basically identical after that. If you go carbon fiber, it takes about two seasons to break even. And that’s without factoring in the cost of replacing o-rings and seals that CO2 chews through faster, or the fact that CO2 tanks have a shorter certification lifespan.

There’s also the scenario where you buy your own HPA compressor or have a buddy with one. A personal fill station is a big investment ($300-$500 for a decent one), but if you split it with a few friends who play regularly, your per-fill cost drops to basically zero after the initial purchase. I know a few groups who’ve done this and they never go back.

The bottom line: CO2 is cheaper on day one. HPA is cheaper (or at least equal) over time, and you get better performance the entire way. For most players who stick with the sport past their first few outings, HPA is the better financial decision.

Temperature and Weather: Where CO2 Falls Apart

I touched on this earlier, but temperature deserves its own section because it’s the single biggest practical difference between CO2 and HPA on the field.

That “11 PSI per degree” stat is technically accurate, but what does it actually feel like when you’re playing? Let me paint the picture.

Say you chrono your CO2-powered marker at 280 FPS on a 75°F afternoon. Everything is great. Now imagine you show up to a fall scenario game and it’s 50°F outside. That 25-degree drop has already reduced your tank’s internal pressure by roughly 275 PSI before you’ve even fired a shot. You’re starting the day at a disadvantage. Your first shots might chrono fine after you’ve adjusted your velocity, but as you start shooting, the cooling effect from gas expansion stacks on top of the already-cold ambient temperature. I’ve seen players’ markers drop below 200 FPS in these conditions. Their paintballs are floating in like slow-pitch softballs. You can literally see them arcing.

Now add rain or high humidity to the mix. Damp, cold air makes the cooling effect even worse. I played a rainy November game years ago where a guy on my team was running CO2 and had to sit out the last two games because his marker was shooting so slow that balls were bouncing off people instead of breaking. That’s not fun for anyone.

With HPA, none of this matters. Compressed air doesn’t care if it’s 30°F or 100°F outside. The regulator delivers the same output pressure regardless. I’ve played in everything from Florida summer heat to early December cold in the mid-Atlantic, and my HPA-powered marker has never given me a velocity issue related to weather. Not once.

Here’s my rough guideline: If you play exclusively in warm weather (above 60°F) and use a mechanical marker, CO2 is fine. The temperature effects exist but they’re manageable. If you play year-round, play in any climate where mornings start below 50°F, or shoot at any kind of volume, HPA removes a variable you don’t want to deal with.

There’s one more wrinkle worth mentioning. On really hot days (90°F+), CO2 can actually spike in pressure and push your velocity over the field limit. This is the opposite problem — instead of shooting slow, you’re shooting hot. Most fields chrono regularly, but if your velocity creeps up between chrono checks because your tank is baking in the sun, you could be shooting dangerously fast without realizing it. HPA doesn’t have this problem.

These professional speedball players use top-of-the-line electronic markers that require the use of an HPA tank.

Which One Should You Buy?

I’ve laid out the technical details, the costs, and the real-world differences. Here’s my straight-up recommendation based on your situation.

You’re buying your first marker on a tight budget: Go with CO2. Seriously, it’s fine. A Tippmann 98 Custom or Cronus with a 20 oz CO2 tank is a proven combo that’ll serve you well while you figure out if you want to commit to the sport. You can always switch to HPA later — the marker doesn’t care. Don’t let anyone tell you that you need HPA to have fun on the field. Check out our list of the best paintball guns and you’ll see plenty of markers that run great on CO2.

You’re playing regularly (once a month or more): Invest in an HPA tank now. Even a basic 48/3000 aluminum tank for $50 will give you consistent performance and save you headaches. The cost difference versus CO2 is minimal when spread over a season, and you’ll appreciate the reliability. If you can stretch to a 68/4500 carbon fiber tank, even better — more shots per fill and lighter weight.

You’re running an electronic marker: HPA is mandatory, full stop. Do not put CO2 through an electronic marker. The pressure fluctuations can damage the solenoid, and the liquid CO2 that occasionally gets past the valve can wreck internal seals and o-rings. Every electronic marker manufacturer specifies HPA. This isn’t optional. You’ll also want to pair it with a quality hopper that can keep up with your firing rate.

You play in cold climates or year-round: HPA, strongly recommended. If you’re dealing with temperatures below 55°F on a regular basis, CO2 will frustrate you. The velocity drops are real and noticeable, and no amount of adjusting your velocity screw will fix a physics problem. Save yourself the aggravation.

You play woodsball a few times a summer with a mechanical marker: Honestly, either one works. If convenience matters and you want to grab a refill at the local sporting goods store on your way to the field, CO2 is a perfectly valid choice. But if the price difference doesn’t bother you, HPA is still the better performer.

The Industry Is Moving to HPA

Both CO2 and HPA have their place in today’s paintball world, but the trend is clear. More and more fields are going HPA-only. This paintball field flat-out banned CO2 in favor of HPA for three reasons:

1. CO2 tanks are more expensive for fields in the long run due to supply and delivery costs of liquid CO2.
2. CO2 refills are more time-consuming because you need specialized fittings and training.
3. HPA performs more reliably under all weather conditions and firing speeds.

New markers coming to market increasingly assume HPA as the default. Many mid-range and all high-end markers are designed for HPA only. Even budget markers under $150 work great with HPA tanks. The writing is on the wall.

That doesn’t mean CO2 is going away tomorrow. Rental fleets at some fields still use CO2 because the tanks are cheap and disposable. Casual players who own a mechanical marker and play a handful of times a year can absolutely stick with CO2 and be perfectly happy. But if you’re investing in your own gear and planning to play for years, HPA is where you should put your money. The performance is better, the costs even out over time, and you’ll never have to wonder if your tank temperature is messing with your shots.