Enter your batch size, tea type, and starter liquid pH to get precise ingredient ratios for your kombucha brew. The Kombucha Brewing Calculator outputs exact amounts of tea, sugar, water, and starter liquid — plus optional SCOBY percentage — so every batch is consistent and dialed in.
Sweet Tea (Water) Volume
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Sugar Required
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Tea Bags Needed
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Starter Liquid
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Recommended SCOBY Size
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Est. Fermentation Time
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Most brewers use 10% starter liquid by volume — so for a 4-liter batch, you'd use about 400ml of starter. You can increase this to 15–20% in warmer climates or when you want a more acidic result faster. Going below 5% risks under-acidifying the batch, which can allow unwanted bacteria to grow.
The standard is around 60–80 grams of sugar per liter of sweet tea. The SCOBY consumes much of this sugar during fermentation, so the final drink is less sweet than the starting liquid. Using too little sugar can stress the culture, while too much can slow fermentation.
A general rule is 2 standard tea bags (or 2 grams of loose leaf tea) per liter of water. Black tea is most commonly used and supports robust SCOBY health. Green and white teas work well but may produce slightly lighter flavor profiles.
A SCOBY should ideally cover the surface area of your brewing vessel. For a 1-gallon jar (roughly 20cm diameter), a SCOBY of at least 300cm² works well. Smaller SCOBYs will still ferment the batch — they'll just grow to fill the surface over time.
First fermentation (F1) typically takes 7–14 days at room temperature (22–28°C). Warmer temperatures speed up fermentation, while cooler temps slow it down. Taste your brew starting at day 7 — it's ready when it reaches your preferred balance of sweet and tart.
Yes. Black tea ferments fastest and produces the most classic kombucha flavor. Green tea yields a lighter, more delicate brew and may ferment slightly slower. White and oolong teas are less common but produce interesting flavor profiles — oolong is a great middle ground between black and green.
Finished first-ferment kombucha should have a pH between 2.5 and 3.5. This acidity is what makes it safe to drink and inhibits the growth of harmful organisms. If your pH is above 4 after 7+ days, your SCOBY may be weak or your starter liquid wasn't acidic enough.
Absolutely. The ratios remain the same regardless of batch size — simply enter your full production volume. For very large batches (100+ liters), consider using multiple SCOBYs to ensure full surface coverage and even fermentation throughout the vessel.