The Quick Answer
Yes, beer is carbonated. Dissolved CO2 - typically 2.2 to 2.8 volumes - creates the fizz, the body, and the aroma release in every sip. Carbonation comes from fermentation (natural) or injection under pressure (forced), and four things kill it: warmth, oxygen, time, and a container that can't hold pressure.
We've been building pressurized growlers in Bend, Oregon since 2013 - over 48,000 orders shipped since 2019, each one engineered around keeping carbonation alive from the first pour to the last.
Nobody asks "is beer carbonated" on a good day
You're here because something went wrong. A growler fill that tasted incredible at the brewery and tasted like a betrayal three days later. A six-pack left in the car for an afternoon that came out tasting like it had been through something. Or you're standing in a kitchen holding a flat beer and wondering what exactly you did to deserve this.
The answer is physics, not karma. And once you understand how carbonation actually works - and what kills it - you'll stop blaming yourself and start blaming your container.
How carbonated is your beer? It depends on the style
Not all beer carries the same fizz. A German wheat beer holds nearly four times the CO2 of a cask-conditioned English bitter, and neither one is doing it wrong.
| Beer style | Carbonation (volumes CO2) | What it feels like |
|---|---|---|
| Cask-conditioned British ale | 1.0-1.5 | Almost still - smooth, low fizz, served from a hand pump |
| Dry stout (Guinness-style) | 1.8-2.5 | Creamy, not fizzy - nitrogen does most of the work |
| American pale ale / IPA | 2.2-2.8 | Medium fizz - crisp, clean, the default for most craft beer |
| Standard American lager | 2.5-2.8 | Bright and sharp - the carbonation you grew up on |
| German/Bohemian pilsner | 2.3-2.8 | Lively, clean finish with a bite |
| Belgian tripel | 2.4-3.0 | Effervescent - almost champagne territory |
| German wheat beer (Weizen) | 2.8-5.1 | Explosive - pour too fast and you'll be wearing it |
Carbonation ranges from Brew Your Own and Home Brew Answers. One "volume" means one liter of CO2 dissolved per liter of beer at standard pressure and temperature.
Why is beer carbonated in the first place?
CO2 does three jobs in beer that nothing else can do.
First, it creates the fizz - the physical sensation on your tongue, which is actually a mild chemical burn from carbonic acid, not just bubbles popping. Your tongue has receptors for it the same way it has receptors for spice. You're not imagining the tingle. It's real chemistry happening on your face.
Second, CO2 carries volatile aroma compounds from the liquid to your nose. It's a delivery vehicle. Take away the carbonation and you take away the smell, which is most of what people mean when they say "taste." This is why flat beer doesn't just feel wrong - it literally smells different, and not in a way anyone would describe as "mellow."
Third, it creates the head. Foam traps aroma, looks right, and tells your brain the beer is fresh before you've taken a sip. It's a trust signal made of bubbles.
Every brewery in the country - all 9,796 of them - puts real effort into hitting an exact carbonation level for every style. That precision survives roughly 30 minutes once the beer hits an open glass, at which point it begins doing whatever it wants. Which is mostly leaving.
How does beer carbonation actually work?
Two methods, and you've had both.
Natural carbonation happens during fermentation. Yeast eats sugar, produces alcohol and CO2 as byproducts. In a sealed container - a bottle, a cask, a keg - that CO2 has nowhere to go, so it dissolves into the beer under its own pressure. This is how beer carbonated itself for thousands of years before anyone thought to attach a gauge to anything.
Bottle-conditioned beers (a lot of Belgian ales, some craft IPAs) still do it this way. The yeast is alive in the bottle, still working, still quietly producing CO2 like a small employee who never goes home. It's the reason those beers change over time, and it's the reason you pour them carefully unless your idea of a good afternoon involves a glass full of sediment.
Forced carbonation is what most beer you'll ever drink has been through. The brewery pumps CO2 from a tank directly into cold beer under pressure. It's faster, more consistent, and lets the brewer hit an exact target without waiting for biology to get around to it.
The science behind both is Henry's Law, named after the English chemist William Henry, who worked this out in 1802: the amount of gas a liquid can hold is directly proportional to the pressure above it. More pressure, more dissolved gas. Less pressure, bubbles escape. It's the reason a sealed bottle stays fizzy and an open one doesn't. It's also the entire operating principle behind every pressurized growler ever made, which isn't something you'd expect a 223-year-old physics equation to be responsible for, but here we are.
The brewing nerds love to argue about which method tastes better. The research quietly settled it: in two controlled blind tastings, tasters couldn't reliably tell naturally carbonated beer from force-carbonated beer of the same style. The panel failed to reach significance in both an IPA (p=0.38) and a Saison (p=0.44). Both methods work. How the CO2 got there matters a lot less than whether it stays.
Is beer fizzy like soda?
Beer is carbonated. Soda is more carbonated. The difference isn't subtle.
Most beers sit between 2.2 and 2.8 volumes of CO2. A typical soda runs 3.0 to 4.0 volumes - roughly 30-50% more. That's why your first sip of beer after a week of nothing but Coke can feel almost flat by comparison, even when it isn't. Your mouth recalibrated, and nobody told it to recalibrate back.
The real difference isn't just quantity. CO2 in beer interacts with proteins from malt to create a stable head - the foam that sticks around. Soda has no proteins to work with, so the bubbles form and pop and that's the end of the relationship. A pint of IPA holds its head for minutes. A glass of Sprite looks abandoned ten seconds after you pour it.
And nitrogen beers - think Guinness, or the nitro cold brews showing up everywhere - are a different situation entirely. A nitro pour uses a gas mix that's 70-75% nitrogen and only 25-30% CO2. Nitrogen produces smaller bubbles, a creamier mouthfeel, and almost no carbonic bite. It's the reason a Guinness cascade looks the way it does and feels closer to drinking something that gently landed on your tongue than something that attacked it.
What kills beer carbonation?
Four things, ranked by how fast they work. This is the section the other articles on the internet forgot to write, and it's the one that actually matters to anyone holding a beer.
1. Temperature. This is the big one, and it's not close. CO2 solubility in liquid nearly halves between 32°F and 68°F - from 3.35 g/L to 1.69 g/L. A beer sitting on the counter physically can't hold as much carbonation as one in the fridge. It's not losing gas because the cap is loose. It's losing gas because warm liquid rejects CO2 the way a full bus rejects one more passenger. There is no room.
Miller Brewing formalized this as the 3-30-300 rule: beer degrades at the same rate stored at 90°F for 3 days, 72°F for 30 days, or 38°F for 300 days. A growler left in a hot car for one afternoon ages as much as one kept in the fridge for a month. This isn't a metaphor. It's the same chemical process running at different speeds.
2. Oxygen. Every time a container opens, air enters. That air contains oxygen, and oxygen does two things: it pushes CO2 out faster, and it creates staling compounds - specifically trans-2-nonenal, the chemical behind that wet-cardboard flavor that tells you a beer has given up on life. That compound is detectable at less than one part per billion. One billionth. It takes almost nothing, and it needs almost nothing.
3. Time. Even sealed, beer doesn't stay fresh forever. A poured beer starts losing carbonation within 30 minutes to an hour. An opened growler goes noticeably flat in 24-36 hours. An unopened standard glass growler holds 3-5 days refrigerated, and if you've ever opened one on day five, you already know "holds" is doing generous work in that sentence.
4. Light. UV light triggers a reaction between hop compounds and sulfur in beer to produce 3-methyl-2-butene-1-thiol - the same chemical found in actual skunk spray. Detectable at one-billionth of a gram per 12 ounces. It happens in as little as 30 minutes of sunlight. The damage is permanent. This is why beer comes in dark bottles and cans, and why a clear glass growler in the sun is essentially a science experiment you didn't sign up for.
Keep it cold and sealed under pressure in something dark. Miss any one and the carbonation starts leaving before you do.
How to keep beer carbonated after you bring it home
The beer industry has been trying to solve this since at least 1942, when food writer M.F.K. Fisher wrote that draft beer "is better in bottles." Eighty-plus years later, we have better answers than "just drink faster."
Keep it cold. Not "sort of cold" or "back in the fridge when I remember." Cold. At 40°F, maintaining 2.4 volumes of CO2 takes about 11 PSI. At 65°F, the same level requires 27 PSI - more than double the pressure just because the temperature went up 25 degrees. Every minute on the counter costs carbonation that no amount of re-capping gets back.
This is why insulation matters as much as the seal. A DrinkTanks Craft Growler keeps beverages cold for 45+ hours - not because cold beer is a nicer experience (it is), but because cold beer is a more carbonated beer. The insulation isn't a luxury feature. It's a carbonation feature that also happens to make your beer cold.
Minimize headspace. The air between the beer and the cap is oxygen with a front-row seat. Beer enthusiasts on Northern Brewer figured this out the hard way: "if it's not holding carb then your cap is leaking... fill it to the top with very little head space." A Brulosophy experiment backed it up - even a glass growler filled to the brim and immediately sealed was indistinguishable from keg-fresh beer after four days (p=0.44). The growler wasn't special. The fill was.
Keep it sealed under pressure. Standard glass growlers with swing-top or screw caps lose significant CO2 within 48 hours because the seal isn't pressure-rated. The beer doesn't go flat because growlers are a bad idea. It goes flat because a flip-top cap at atmospheric pressure is a one-way exit for dissolved gas, and dissolved gas does not need to be asked twice.
Pressurized growlers close the gap entirely. In another blind test, a Brut IPA stored in a pressurized growler for three days was indistinguishable from keg beer (p=0.70). No oxidation. No carbonation loss. The kind of result that makes you wonder what everyone was doing with glass growlers all those years, besides watching their beer get worse.
That's what DrinkTanks' dual-bail closure is built for - holding pressure on the beer so the CO2 stays dissolved instead of leaving. Our growlers keep carbonation for up to 30 days unopened. A standard glass growler is on borrowed time after day two.
Keep it dark. Stainless steel handles this on its own - no UV gets through. If you're drinking from glass, keep it refrigerated and out of any window. Thirty minutes of sunlight does damage a refrigerator can never undo.
What we see from 13 years of building growlers
Brewery owners have been writing the growler's obituary since crowlers showed up. Brooklyn Brewery's Garrett Oliver compared bringing a growler home to "bringing restaurant food home to microwave it." Reach Break Brewing's Josh Allison said "glass growlers are pretty much dead."
They're right about glass. They're describing the wrong growler.
The complaints are always the same three: the seal leaks, the temperature climbs, and the beer quality deteriorates noticeably between Friday evening and Sunday. Those are container problems, not beer problems. A vacuum-insulated, pressure-sealed stainless steel growler with a dual-bail closure fixes all three - and blind tests can't tell the difference between a pressurized growler and a keg. Nobody has ever made that claim about a glass jug with a flip-top.
We know this because we've shipped over 48,000 orders since 2019. The reviews that stay with you are the people using the same cup daily for eight years and the ones who say "all of my other growlers are collecting dust." Our Craft Growler keeps beverages cold for 45+ hours. Carbonation holds up to 30 days unopened. Those aren't marketing numbers plucked from a press release - they're engineering specs backed by a lifetime warranty.
The growler market isn't dying. It's projected to reach $823.6 million by 2034, with the stainless steel segment growing at over 5% a year. Craft brewery visits are up to 3.5 per person per year. And 79% of craft beer drinkers have found a beer while traveling they wish they could take home.
The question was never whether the growler is dead. It's whether the glass one deserved to be.
FAQ
Is all beer carbonated?
Almost all. The vast majority of beer contains dissolved CO2 at levels between 1.0 and 5.1 volumes. The exceptions are traditional cask ales served via hand pump (still lightly carbonated at 1.0-1.5 volumes) and a handful of experimental still beers. If you bought it at a store or ordered it at a bar, it's carbonated.
Can beer lose its carbonation?
Yes, and it starts the moment the seal breaks. A poured beer loses CO2 within 30 minutes. An opened growler goes flat in 24-36 hours. An unopened standard growler holds 3-5 days refrigerated. Temperature accelerates everything - warm beer loses carbonation faster because CO2 is less soluble in warmer liquid.
Why does draft beer taste different from bottled or canned?
Three things: freshness, serving temperature, and carbonation method. Draft beer travels a shorter path from keg to glass, stays cold through pressurized lines, and often carries slightly different carbonation than the packaged version. A container that replicates those conditions - cold, pressurized, sealed - is the closest you'll get to tap quality at home.
How long does beer stay carbonated in a growler?
Standard glass growler: 3-5 days unopened, refrigerated. After opening, 24-36 hours before noticeable flatness. A pressurized stainless steel growler like a DrinkTanks Craft Growler: up to 30 days unopened, with carbonation maintained by the dual-bail closure holding positive pressure on the beer.
Is flat beer safe to drink?
Yes. As Firestone Walker's Craig Thomas noted, "pathogens cannot live in beer, so from a health standpoint, beer cannot go bad." Flat beer won't hurt you - it'll just taste like something that started the day with ambition and lost it around noon. The alcohol, pH, and hop acids create conditions where harmful bacteria can't survive.
What beer has the most carbonation?
German wheat beers (Weizen/Weissbier) at 2.8-5.1 volumes of CO2 - roughly double a cask ale and approaching soda territory. Belgian tripels and gueuzes also run high at 2.4-3.0 volumes. If you've ever had a hefeweizen erupt when you opened it a little too enthusiastically, you've met the top of the carbonation chart personally.
Your beer deserves better than a glass jug and a wish
You now know more about beer carbonation than most of the internet. Keep it cold, keep it sealed, keep it pressurized, keep it dark. The container either does the work or watches the carbonation leave.
If your current setup involves crossing your fingers and drinking fast, the Growlers collection has every size we make - each one built to keep beer the way it tasted at the tap. Not sure how many beers fit in a growler? We wrote a whole post about it. Wondering whether you can reuse one? That too.
Free shipping on orders over $149.
About the author
Nicholas Hill - Founder & CEO, DrinkTanks. Building pressurized drinkware in Bend, Oregon since 2013.