Reserve starter volume
4 L × 10% = 0.4 L starterThe remaining 3.6 liters become the fresh sweet-tea portion.
← All calculatorsSWEET TEA, SCALED
Kombucha Sugar Calculator
Set your finished batch volume and get the sweet tea, sugar, tea, and mature starter liquid required for the first fermentation.
HOW THE MATH WORKS
Separate the starter from the fresh tea
A 4-liter target with 10% starter contains 400 mL of mature kombucha and 3.6 liters of fresh sweet tea. Sugar and dry tea are calculated from that fresh-tea portion.
Scale the sugar
3.6 L × 70 g/L = 252 gDissolve sugar in hot tea, then cool fully before adding starter.
PRACTICAL STARTING RANGE
Know what each input controls
| Input | Starting point | Purpose |
|---|---|---|
| Starter liquid | 10–20% | Introduces the culture and immediately acidifies fresh tea. |
| Sugar | 50–90 g/L | Supplies fermentable sugar; final residual sugar will vary. |
| Loose tea | 1.5–6 g/L | Provides tea compounds and determines brew strength. |
| First fermentation | 7–14 days | Taste and acidity change with culture, time, and temperature. |
AFTER THE FIRST FERMENTATION
Refrigeration, carbonation, and alcohol matter
Sealed secondary fermentation can build significant pressure. Colorado State University warns that extended room-temperature storage in sealed bottles can cause containers to burst and recommends refrigerating finished kombucha.
Fermentation can also produce alcohol. In the United States, the TTB regulates kombucha that reaches 0.5% alcohol by volume or more at any point during production or after bottling.
COMMON QUESTIONS
Kombucha sugar calculator FAQ
How much sugar should I use for kombucha?
A practical starting range is 50–90 grams of sugar per liter of fresh sweet tea. The calculator defaults to 70 g/L. Sugar is food for the culture, so this input is not the same as the amount of sugar remaining after fermentation.
How much starter liquid does kombucha need?
Ten percent of the finished batch is a common starting point. Some published home-brewing guidance uses roughly 1–2 cups per gallon. Starter strength varies, so measure the starting pH rather than relying on volume alone.
Does the SCOBY pellicle count as starter?
No. In this calculator, starter means mature, unflavored liquid kombucha. The cellulose pellicle may carry microbes, but the acidic liquid is what immediately lowers the fresh tea’s pH.
Can I calculate kombucha in gallons?
Yes. Select US gallons and the calculator will show both metric and imperial results. Ingredient ratios remain the same.
When should I add the starter liquid?
Add mature starter only after the sweet tea has cooled completely to room temperature. Hot tea can damage the culture.
Research-based sources
- Colorado State University Extension: Understanding and Making Kombucha — ingredient ranges, fermentation, refrigeration, and spoilage guidance.
- Utah State University Extension: Homemade Kombucha — weight-based recipe and starting-pH guidance.
- Peer-reviewed review of kombucha and kefir microbiomes — typical tea, sugar, starter, and fermentation ranges.
- U.S. Alcohol and Tobacco Tax and Trade Bureau: Kombucha — alcohol threshold and regulatory context.