About six bar
How much pressure is in a bottle of sparkling wine?
A bottle of Champagne typically holds around 6 bar of pressure at 20 degrees Celsius, roughly two to three times that of a car tire. Sekt requires at least 3.5 bar, and Perlwein has 1 to 2.5 bar. The pressure comes from the sugar in the dosage de tirage: about 24 grams per liter produces roughly 6 bar.
How does the pressure in a sparkling wine bottle develop?
During the second fermentation, the yeast converts the sugar from the dosage de tirage into alcohol and carbon dioxide. Inside the sealed bottle, the gas cannot escape. A small portion collects in the headspace under the closure, while most of it dissolves into the wine. The more sugar that ferments, the more gas is produced and the higher the pressure rises. Once the sugar is used up, the pressure stabilizes.
A rule of thumb in wineries: roughly four grams of sugar per liter produces about one bar of pressure. This gives the standard dosage de tirage of around 24 grams per liter for about six bar. Adding less sugar produces a gentler mousse. Some wines are deliberately made this way, such as Franciacorta Satèn, which stays below 5 atmospheres instead of around six. The name recalls satin, meant to evoke just how soft the mousse should feel.
What minimum pressure does the law require?
EU law measures the overpressure at 20 degrees Celsius in the sealed bottle. Sparkling wine requires at least 3 bar, and quality sparkling wine — Sekt in Germany — at least 3.5 bar. For bottles under 25 centiliters, 3 bar is sufficient even for quality sparkling wine. Perlwein ranges between 1 and 2.5 bar, while aromatic quality sparkling wine such as Asti requires at least 3 bar. Which category appears on the label therefore also depends on pressure.
Most bottle-fermented sparkling wines sit well above these minimums, with Champagne typically around six bar. This figure isn't a legal requirement but standard cellar practice. It produces the robust yet fine mousse the houses aim for, while staying well within what a sparkling wine bottle can withstand. Pét-Nats, by contrast, have no fixed pressure and vary considerably depending on when they're bottled.
Why does pressure depend on temperature?
Cold wine holds carbon dioxide better than warm wine. This is simple physics: gases dissolve more readily in cold liquids. In a chilled bottle, more carbon dioxide therefore stays dissolved in the wine, and the pressure in the headspace drops. In a warm bottle, more gas escapes from the wine, and the pressure rises. That's why the law states all values at 20 degrees Celsius — only then can they be meaningfully compared.
In practice, this means: a warm sparkling wine foams over violently when opened, losing a lot of carbon dioxide all at once. Well chilled, the gas stays in the wine longer and rises steadily in fine streams of bubbles. Storage matters too: excessive heat puts strain on both bottle and cork. How to open sparkling wine safely and without a loud pop, and at what temperature to serve it, is covered in the guide to serving.
Bottle, cork, wire cage: built for the pressure
Six bar presses against every square centimeter of glass. Sparkling wine bottles are therefore made of thicker, heavier glass than still wine bottles and have a deeply indented base that helps distribute the pressure. The cork must hold too. It's often made of agglomerated cork with discs of natural cork at the base, secured by a metal cap, the plaque, and a wire cage, the muselet.
For Sekt b.A., German wine regulations even mandate this equipment: a sparkling wine bottle, a mushroom-shaped stopper, a retaining device and foil; only bottles up to 0.20 liters may be sealed differently. Perlwein, with its lower pressure, gets by with simpler closures. In Italy, Frizzante is often held in place with a piece of string called spago. The high pressure is also the reason why a sparkling wine cork should never be pointed at anyone.