Kombucha Carbonation Calculator

Enter your bottle size, carbonation target and F2 temperature

Bottle / Batch Volume

Volume of your F2 bottle or batch

F2 Fermentation Temperature

°C

Warmer kombucha holds less dissolved CO2

Carbonation Target

▾

Sets a typical target CO2 level for the style

Weigh table sugar, or measure fruit juice by volume, directly into each bottle before sealing rather than dosing the whole batch at once.

Bottling supplies: Swing-top or pressure-rated bottles make it easy to check carbonation progress without risking a standard cap.As an Amazon Associate we earn from qualifying purchases.

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Next step: Check your hard kombucha's ABV from original and final gravity.

Hard Kombucha ABV Calculator →

How Kombucha Carbonation Works

Second fermentation (F2) carbonates kombucha the same way bottle conditioning carbonates beer or cider: a small amount of extra fermentable sugar is sealed into the bottle with the existing culture, and the CO2 produced as that sugar ferments has nowhere to escape, so it dissolves back into the kombucha instead.

Where kombucha differs is the baseline. Beer and cider are usually gravity-tested before bottling, so their residual dissolved CO2 at a given temperature is fairly predictable. Kombucha is rarely gravity-tested, and the SCOBY culture can still have some residual activity going into F2, so treat the residual CO2 estimate here as a reasonable starting point rather than an exact figure, and adjust future batches based on how carbonated the last one turned out.

CO2 to add (volumes) = Target volumes − Residual volumes at F2 temperature

Table sugar and fruit juice are alternatives, not a combined dose. Table sugar is a clean, predictable, nearly fully fermentable option. Fruit juice adds flavour along with the sugar, but its exact sugar content varies by fruit and brand, commonly around 10-15 Brix, so the calculated amount is a solid starting point rather than an exact figure.

Avoiding Over-Carbonation

Over-carbonating is a genuine safety issue, not just a quality one. Excess CO2 pressure inside a sealed glass bottle can cause it to fail, sometimes violently. This risk is worth taking seriously with kombucha specifically, since the SCOBY culture's fermentation activity is less predictable batch to batch than an isolated brewer's yeast, and a batch that ferments more vigorously than expected can build pressure faster than the calculation assumes.

Use bottles actually rated for carbonation, such as swing-top bottles designed for pressure, and consider "burping" bottles briefly during the first few days of F2 to release excess pressure if they feel rock-hard. Never add extra sugar or juice beyond a calculated dose on the assumption that more carbonation is simply better, and store F2 bottles somewhere they can be safely contained if one does fail.

More Brewing & Fermentation Calculators

Hard Kombucha ABV New

Calculate ABV from original and final gravity

Beer Priming Sugar New

Corn sugar, table sugar or DME for bottle carbonation

Yeast Nutrients Active

DAP, Fermaid-K and Fermaid-O dosing

Bottle Yield Active

How many bottles your batch will fill

Blending Active

Blend two batches to a target ABV

Dilution Chart Active

Water-to-add reference table for any ABV

Frequently Asked Questions

How much sugar or juice do I need for kombucha carbonation?

It depends on your bottle size, target carbonation level, and the temperature during second fermentation, since warmer kombucha holds less dissolved CO2 and needs a smaller top-up. A typical 473 mL (16 oz) bottle aiming for moderate carbonation needs roughly 1-2 teaspoons of table sugar or 1-2 tablespoons of fruit juice, though this varies enough with temperature and target that it is worth calculating for your specific setup.

What is the difference between table sugar and fruit juice for kombucha F2?

Table sugar (sucrose) is nearly fully fermentable and gives a clean, predictable carbonation with no flavour change. Fruit juice adds sugar and fruit flavour at the same time, but its exact sugar content varies by fruit and brand, commonly 10-15 Brix, so the calculated amount is a solid starting point rather than an exact figure.

Why does temperature matter for kombucha carbonation?

Kombucha already holds some dissolved CO2 from fermentation, and how much it holds depends on temperature: colder kombucha retains more CO2, warmer kombucha retains less. This calculator subtracts that residual CO2, estimated from your F2 temperature, from your target level, so you only add sugar or juice for the gap that is actually missing.

Can kombucha bottles actually explode from over-carbonation?

Yes, and it is a real risk, not an exaggeration. Kombucha's SCOBY culture can ferment more vigorously and less predictably than an isolated brewer's yeast, so a batch can build pressure faster than expected. Use swing-top or other pressure-rated bottles, consider briefly burping bottles during the first few days of F2, and never add extra sugar or juice beyond a calculated dose.

How is this different from a beer priming sugar calculation?

The underlying physics, how much CO2 a given amount of sugar produces and how much a liquid can hold at a given temperature, is the same. The difference is that beer is normally gravity-tested before bottling, giving a reliable starting point, while kombucha rarely is, and its active culture behaves less predictably than isolated brewer's yeast. Treat the kombucha result as a well-reasoned starting point to refine over a few batches, rather than as precise as a tested beer priming calculation.