How much sugar, tea and starter liquid your jar of kombucha needs, scaled from the tested NCHFP gallon recipe, with checks for starter pH and room temperature.
Kombucha Calculator - Sugar, Tea and Starter per Gallon
How much sugar, tea and starter liquid your jar of kombucha needs, scaled from the tested NCHFP gallon recipe, with checks for starter pH and room temperature.
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Kombucha first fermentation, scaled to your jar
Enter the size of the batch in gallons, quarts or liters and this kombucha calculator scales the tested recipe from the National Center for Home Food Preservation: sugar, tea bags or loose tea, hot and cold water, and how much starter liquid goes in. Then it sorts your room temperature and the pH of your starter against the rules the extension services publish.
Five settings before the tea goes in
- Batch size and unit - the sweet tea you will brew, from 0.25 to 13 gallons, 1 to 52 quarts or 1 to 50 liters.
- Tea - black or green. Green needs more than twice the bags.
- Bags or loose - bags are rounded to whole ones, loose tea to the nearest half tablespoon.
- Room temperature - one of four bands, or not sure.
- Starter pH - from a pH strip dipped in about a tablespoon of starter, or not tested.
The gallon recipe, piece by piece
Everything the calculator does starts from this one gallon. Each card is a line of the NCHFP recipe, with the starter amount from UC Master Food Preservers, because the NCHFP recipe lists the starter without a measure.
From a quart jar to a 5 gallon crock
The recipe scales by volume, so a half batch is half of everything. The tea bag column shows the exact figure; the calculator rounds it to whole bags for you.
| Batch | Sugar | Black tea bags | Green tea bags | Starter |
|---|---|---|---|---|
| 1 quart | 50 g | 1.5 | 3.25 | 1/4 to 1/2 cup |
| 2 quarts | 100 g | 3 | 6.5 | 1/2 to 1 cup |
| 1 gallon | 200 g | 6 | 13 | 1 to 2 cups |
| 2.5 gallons | 500 g | 15 | 32.5 | 2 1/2 to 5 cups |
| 5 gallons | 1,000 g | 30 | 65 | 5 to 10 cups |
In liters the same arithmetic gives, for a 4 liter jar, 211 g of sugar, 6 black tea bags and 250 to 500 ml of starter.
How the result sorts pH and room temperature
Two checks run next to the recipe. Neither changes the amounts; they tell you whether to go ahead and what to expect.
| Reading | What the result says |
|---|---|
| Starter pH 4.0 or lower | meets the NCHFP rule, go ahead |
| Starter pH 4.1 to 4.5 | NCHFP says do not use it; Utah State would accept it below 4.5 |
| Starter pH above 4.5 | fails both, get fresh starter liquid |
| Room below 68 °F | slower than the tested 7 to 10 days |
| Room 68-77 °F | the NCHFP test range |
| Room 78-85 °F | faster; the Utah State range; taste from day 7 |
| Room above 85 °F | outside every range given, check early |
Three extension recipes that almost agree
The National Center for Home Food Preservation at the University of Georgia ferments 7 to 10 days at 68-77 °F and wants starter at pH 4.0 or lower. Its FAQ adds that brewing this way left trace alcohol, under 0.016% ABV, and that longer fermentation makes more.
Utah State University Extension runs warmer, 75-85 °F, for 7 to 10 days and allows up to 21. Its pH line is below 4.5, with a tablespoon of white vinegar if the start misses it.
UC Master Food Preservers in San Diego County use 1 to 2 cups of starter per gallon, 64-79 °F, and 7 to 14 days. The calculator takes the NCHFP recipe as the base, since its FAQ describes the research behind the amounts, and the result says where the other two would answer differently.
Kombucha brewing questions
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