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What makes cider fizzy

Why is some cider fizzy and some flat?

In short

Fizz is dissolved carbon dioxide. Fermentation produces it in large quantities, but in an open vessel it escapes, which is why a cider fermented and matured in the usual way and then bottled is completely still.

To make cider sparkling, the gas has to be trapped or added. Either fermentation is allowed to continue in a sealed container, or carbon dioxide is dissolved into the finished cider under pressure.

Still cider is not a failure to carbonate. It is the older form, it remains the norm in Spanish, much English farmhouse and much American traditional practice, and carbon dioxide changes how a cider tastes as well as how it feels.

Four carbonation bands measured in volumes of dissolved carbon dioxide, with the pressure each implies at 20 °C.

Described in full

The unit: A volume of carbon dioxide is the volume of gas, at standard conditions, dissolved in one volume of liquid. It is the unit cidermakers and brewers work in because it maps directly to pressure at a given temperature.
Still, nought to one volume: No perceptible bead. Sidra natural and most still perry sit here. Nothing needs to be held in: there is no meaningful pressure inside the container.
Pétillant, one to two and a half volumes: A light prickle rather than a mousse. French cidre bouché and much English farmhouse cider live in this band, at up to roughly two bar of gauge pressure at 20 °C.
Sparkling, two and a half to four volumes: The band most commercial cider is carbonated to. Roughly two to three and a half bar at 20 °C, which is why crown caps and pressure-rated bottles become necessary rather than optional.
Fully sparkling, four to six volumes: Traditional-method cider and Champagne-style sparkling perry. At six volumes the gauge pressure at 20 °C is around six bar, which needs a sparkling bottle and a wired or crown closure.
Temperature matters more than intuition suggests: The same dissolved gas exerts markedly less pressure cold than warm. A bottle safe in a cellar can be dangerous in a car in summer, and every pressure figure here is quoted at 20 °C for that reason.
Where the bands come from: They are descriptive conveniences, not legal categories. The boundary between pétillant and sparkling in particular is a matter of usage, and different traditions place it differently.

Where the gas comes from

Fermenting one gram of sugar produces roughly equal masses of ethanol and carbon dioxide. A fermenting vessel therefore throws off a very large volume of gas, and in an open or airlocked vessel almost all of it leaves. What remains dissolved at atmospheric pressure is small, and it dissipates during racking and maturation.

Carbon dioxide dissolves in liquid in proportion to the pressure above it, and less readily as temperature rises. That is the whole physics of carbonation: to get more gas in, either raise the pressure or lower the temperature, and to keep it in, keep the container sealed.

When a bottle is opened, the pressure drops to atmospheric and the cider is suddenly holding more gas than it can. The excess comes out of solution, nucleating on imperfections in the glass and on particles in the liquid, which is why bubbles rise in streams from particular points rather than uniformly.

The three routes

How carbonation is achieved, and what each route implies.
Route	What happens	Typical result	Where it is traditional
Retained fermentation gas	The cider is sealed into bottle or keg before fermentation has finished, and the remaining ferment pressurises the container	Light to moderate sparkle; sediment; some residual sweetness	Norman cidre bouché; traditional English bottled cider
Second fermentation in a sealed container	A dry cider is dosed with sugar and yeast and sealed, in bottle (bottle conditioning) or in a pressurised tank (tank conditioning)	Fine, persistent mousse; sediment where done in bottle	English bottle-conditioned cider; sparkling perry; traditional-method sparkling cider
Forced carbonation	Carbon dioxide is dissolved into the finished cider under pressure before or during packaging	Any level of carbonation the producer chooses, precisely repeatable; no sediment	Most keg and canned cider worldwide; sidra espumosa in its gasified form

Carbonation can be a regulatory boundaryIn the United States, the hard cider tax rate applies only where carbonation does not exceed 0.64 grams of carbon dioxide per 100 millilitres. A cider carbonated beyond that is taxed as a sparkling wine, which is a substantially higher rate. Carbonation level is therefore a commercial decision as well as a stylistic one there.

What carbonation does to the taste

Dissolved carbon dioxide is not only a texture. Some of it reacts with water to form carbonic acid, which is detected as a mild sourness and contributes a distinct tingling sensation through the trigeminal nerve rather than through the taste buds. A sparkling cider therefore tastes sharper than the same liquid poured flat, at identical acid and sugar levels.

It also changes aroma delivery. Rising bubbles carry volatile compounds to the surface and release them, so a sparkling cider presents its aroma more forcefully and more quickly, and loses it faster. A still cider releases its aroma slowly and rewards being left in the glass.

The practical consequence for a drinker is that carbonation shifts the balance. A cider that seems well balanced flat can seem thin and sharp sparkling, and a cider that seems slightly heavy still can be lifted by gas. Producers choose the level with this in mind.

Pétillant, sparkling and still

The vocabulary is loose and largely descriptive. Still means no perceptible carbonation. Pétillant, or frizzante, or lightly sparkling, describes a gentle prickle. Sparkling describes a full mousse of the kind associated with sparkling wine. There is no general legal boundary between them for cider, though sparkling-wine rules define pressure thresholds where the sparkling-wine vocabulary is used.

Spanish practice makes the distinction structural rather than descriptive. Sidra natural is still, and what appears as a brief foam when it is poured from a height is not dissolved gas but air whipped into the liquid, which collapses within seconds. Sidra espumosa is a separate, genuinely sparkling category.

Also answered on this page

Questions this page covers, so you can tell at a glance whether it is the one you want.

Why is my cider flat?
What is pétillant?
Does fizzy cider taste more sour?
Why is Spanish cider not fizzy?
How do producers control the level of fizz?

What people ask next

Questions readers ask about the things this page mentions. Each one goes to the section that answers it rather than to a page written to receive the question.

How is cider carbonated — Either by dissolving carbon dioxide into finished cider under pressure, or by letting a small second fermentation produce the gas inside a sealed bottle or tank. The first is faster and more repeatable; the second leaves sediment and a finer bead.
What does bottle conditioned mean on a cider
Where does the fizz in cider come from — Either from fermentation trapped in a sealed container, or from carbon dioxide dissolved into the cider under pressure before filling. The French cider appellations permit only the first, and require at least 1.0 to 1.5 bar at 20 °C depending on the name.
Why is my bottled cider flat — Either there was no viable yeast left to ferment the priming sugar, or the bottles are not sealing, or it is simply too cold and needs longer somewhere warmer. Two to three weeks at room temperature is the usual minimum.
Is cider meant to be still or sparkling
What is tank conditioning

Sources

What this page rests on. Where a source is marked as registered rather than read, CiderHQ is recording that the body is authoritative on the subject without claiming to have worked through the document itself. See our evidence policy for what each state means.

The Science of Cidermaking and associated technical writing
Andrew Lea · reference work · passage verified 2026-08-24
Written by a food chemist who worked at Long Ashton on apple phenolics. Unusual among specialist cider writing in that it is primary-research-adjacent: the author is describing work he did, and cites the literature. This is why it is registered at tier 1 for chemistry while a general cider book is not.
The New Cider Maker’s Handbook: A Comprehensive Guide for Craft Producers
Claude Jolicoeur, Chelsea Green Publishing, 2013. ISBN 9781603584739 · reference work · bibliographic record verified, not opened 2026-08-25
Bibliographic record verified on 2026-08-25 against the Open Library union catalogue: Chelsea Green Publishing, 2013, ISBN 9781603584739, one edition recorded. That establishes the citation points at a real book in a stated edition, which is what a citation needs and is all it establishes. No copy was opened and nothing is quoted from it. The book itself is in print and not digitised in any open collection; where CiderHQ needs a figure from this territory it uses an accessible research source instead and says so.
Cider and perry production technical training material
Peter Mitchell / Cider and Perry Academy · reference work · registered as competent for this subject
Searched again on 2026-08-25 and it remains the one printed source here that a bibliographic check cannot fix, because it is not a published work with an edition. It is course material issued to participants of a training programme, so there is no catalogue record to verify, no ISBN, and no lawful public copy. Its state stays `registered` for that reason rather than through inattention.
Hard cider tax class and labelling requirements
Alcohol and Tobacco Tax and Trade Bureau (TTB) · regulator · retrieved 2026-08-24
Opened on 2026-08-24. The address CiderHQ had registered — ttb.gov/wine/hard-cider — now returns 404; the bureau publishes its cider material at ttb.gov/cider/cider-resources, and the record has been corrected. The substantive hard cider definition is in 27 CFR §§24.10 and 24.331, which CiderHQ cites directly and has verified to the passage; this page is the regulator’s own gateway and its industry circular pointer, not the operative text.

Where to go next

Learn about cider — The rest of the introductory material, grouped by the question it answers.
Glossary — Any word on this page you did not recognise, defined in one or two sentences.
Comparisons — What separates cider from the drinks it is most often confused with.