CO2 and pressure in the bottle
Dissolved CO2 · Henry's law · pressure vs temperature
A standard bottle of champagne holds about 12 g/L of dissolved CO2, roughly 9 g per 75 cL bottle, all of it made by the second fermentation.1 The gas above the wine presses on the cork at about 4.7 bar at 6 °C and about 7.5 bar at 20 °C.2
Where the gas comes from
The fizz in champagne is made in the bottle. During the prise de mousse, yeast ferments the sugar added at tirage. In the Reims calculation, 24 g/L of added sugar gives about 9 g of CO2 (0.2 mole) in every 75 cL bottle.2 The bottle is closed, so the gas cannot leave. Most of it dissolves in the wine, and a small part stays in the headspace under the cork. One model of a standard bottle used a headspace of 25 mL above 0.75 L of wine.1
Papers from the GSMA laboratory in Reims put the dissolved CO2 of a standard champagne at about 12 g/L; samples disgorged early held about 11 g/L.1 The wine used in a 2010 pouring study held 11.4 g/L before it was poured.4
Henry's law
Gas and wine share the CO2 according to Henry's law: the amount dissolved is proportional to the partial pressure of CO2 in the headspace. For champagne at 25 °C the constant is about 1.21 g per litre per bar.3,2 CO2 is less soluble in warm liquid. When the bottle warms up, some gas leaves the wine for the headspace, and the pressure rises.
Pressure and temperature
| Temperature of the bottle | CO2 pressure under the cork |
|---|---|
| 6 °C | about 4.7 bar |
| 12 °C | about 5.8 bar |
| 20 °C | about 7.5 bar |
Values from Liger-Belair et al., Scientific Reports 2017.2 A later study of cork popping used 7.5 bar for bottles at 20 °C and 10.2 bar at 30 °C.3 This is why a warm bottle opens with more force: see the flight of the cork.
After the cork comes out
Once the bottle is open, the headspace falls to normal air pressure, but the wine still holds far more CO2 than it can keep. A review of food fluid mechanics (a preprint) gives a supersaturation ratio of about 4 just after uncorking: the wine holds about five times the equilibrium amount.5 This excess is what escapes as bubbles in the glass, described on how a bubble is born. Pouring is the step that loses the most of it: see pouring and CO2 loss.
Two figures for the same bottle
Comité Champagne gives the pressure of a finished bottle as 6 bar at 20 °C.6 The research values above are higher at the same temperature (about 7.5 bar). They come from measurements on the bottles used in those studies, so both figures are shown with their sources.
See also
Sources
- Elsevier (author PDF hosted by LMU Munich SFB 1064). Liger-Belair G., Bourget M., Cilindre C., Pron H., Polidori G. Champagne cork popping revisited through high-speed infrared imaging: the role of temperature. Journal of Food Engineering 116: 78-85. DOI 10.1016/j.jfoodeng.2012.11.006 (2013)
- Nature Publishing Group. Liger-Belair G., Cordier D., Honvault J., Cilindre C. Unveiling CO2 heterogeneous freezing plumes during champagne cork popping. Scientific Reports 7: 10938. DOI 10.1038/s41598-017-10702-6 (2017)
- AAAS (full text read via Europe PMC, PMC6754238). Liger-Belair G., Cordier D., Georges R. Under-expanded supersonic CO2 freezing jets during champagne cork popping. Science Advances 5(9): eaav5528. DOI 10.1126/sciadv.aav5528 (2019-09)
- American Chemical Society (article PDF hosted on acs.org). Liger-Belair G., Bourget M., Villaume S., Jeandet P., Pron H., Polidori G. On the losses of dissolved CO2 during champagne serving. J. Agric. Food Chem. 58(15): 8768-8775. DOI 10.1021/jf101239w (2010-07-13)
- Mathijssen A.J.T.M., Lisicki M., Prakash V.N., Mossige E.J.L. Culinary fluid mechanics and other currents in food science. arXiv:2201.12128v2 (review) (2022-10-14)
- Comité Champagne (champagne.education). Fiche Élaboration du Champagne (FR) (2024-05)
Facts checked on 2026-10-19