Kombucha Sugar Calculator (Second Fermentation)
Enter your bottles and pick a sweetness level to get exactly how much sugar or fruit juice to add for carbonation - per bottle and for the whole batch.
Results
- Total sugar
- 36 g
- Standard
- 12 g/L · 15% juice
How second fermentation works
In the bottle, yeast consumes the added sugar and produces CO2 that dissolves into the liquid. Roughly 1-2 teaspoons of sugar per 500 ml (8-16 g/L) is the common range; fruit juice adds both sugar and flavor at 10-20% of volume. Most of the added sugar is consumed within a few days at room temperature.
Sweetness levels compared
| Level | Sugar per liter | Juice share | In the bottle |
|---|---|---|---|
| Light | 8 g/L | 10% of volume | Slow carbonation, mostly tart. Good for long 2F or warm rooms. |
| Standard | 12 g/L | 15% of volume | Balanced fizz in 2-4 days at room temperature. The default choice. |
| Sweet | 16 g/L | 20% of volume | Fast, strong carbonation and noticeable sweetness. Watch pressure closely. |
Carbonation pressure grows with sugar. Stay near or below the standard level, use pressure-rated bottles, and refrigerate before opening.
Frequently asked questions
How much sugar per bottle of kombucha?
The common range is 8-16 g per liter, which is about 1-2 teaspoons per 500 ml bottle. Start at the standard 12 g/L, and reduce it if your kitchen is warm - carbonation builds faster there.
Can I use fruit juice instead of sugar?
Yes. Juice of 10-20% of the bottle volume is the usual range and brings its own flavor. Fresh-pressed and fruit-puree additions work too; account for their sugar content rather than adding extra sugar on top.
How long does second fermentation take?
Typically 2-4 days at room temperature (20-25 C), depending on sugar level, temperature and culture activity. Refrigerate once carbonated to pause fermentation and reduce pressure.
Is it safe to add more sugar for extra fizz?
Carbonation pressure scales with sugar. Beyond about 2% sugar the risk of over-carbonation and bursting bottles grows sharply. Use pressure-rated bottles, stay near the standard level, and chill before opening.