How to Make Kombucha in Bulk, With a Scaling Calculator

Kombucha in bulk is sweet tea, fermented: write the tea, sugar and starter as percentages, brew a concentrate hot, top it up with cool water, add a tenth of the batch as starter from the last one, and ferment in a fermenter sized to the run. Check the pH before flavoring, bottle cold, and test for alcohol on every batch, because kombucha keeps fermenting in the bottle if it's let warm up. Done this way, a brewer that fermented a gallon jar makes about 395 bottles from a 50-gallon fermenter, and the cost of a 16-ounce bottle falls from $4.23 to $1.53. Below is the recipe at two sizes, the steps, the loss, what a bottle costs at each size, and a free scaling calculator.

The short version

• Write tea, sugar, starter and fruit as percentages.
• Brew a hot concentrate, then cool water brings it under 85°F.
• Add a tenth of the batch as starter from the last batch.
• Ferment 7 to 14 days; check the pH before flavoring.
• Bottle cold and keep it cold.
• Test every batch for alcohol.
• TaroStack keeps the recipe by weight, takes each batch's ingredients off stock and checks its yield. More below.

The recipe, by percentage

Brightwater Ferments, the made-up fermented foods maker in Portland, Oregon, I use in these examples, brewed kombucha a gallon jar at a time before buying a 50-gallon fermenter. The recipe, weighed:

The 420 pounds cost $113.65 in ingredients, nearly all of it fruit purée, sugar and tea; the water and starter cost close to nothing. The bottles cost more than what goes in them. The year is in kombucha business plan.

The steps, at 420 pounds

1. Brew the concentrate. Tea steeped in hot water, sugar dissolved, by weight.
2. Cool it with water. Cold filtered water to the batch weight, until it's under 85°F.
3. Add the starter. A tenth of the batch from the last batch, and the culture.
4. Ferment. 7 to 14 days at about 75 to 80°F, tasted and pH-tested toward the end.
5. Flavor. Fruit purée stirred in for a short second fermentation.
6. Chill, filter and bottle. Cold-crashed, filtered, bottled and capped, straight into the cooler.
7. Test and label. A bottle from the batch tested for alcohol; every bottle labeled with the batch's lot, the date and "Keep refrigerated".

A batch takes about 8 hours of labor, most of it bottling.

What a bottle costs at each size

Fruit purée by the pail, sugar by the sack and tea by the kilo cut the ingredients nearly in half, and the labor falls from 7.5 minutes a bottle to about 1.2. The bottle, cap and label are more than half a bottle's cost. When a co-packer makes more sense is in kombucha co-packer, and the margins in kombucha profit margin.

Alcohol and the cold

Kombucha makes a little alcohol as it ferments, and at 0.5% alcohol by volume or more it counts as an alcoholic beverage under federal law, with a different set of rules and taxes. Bottles kept cold stay under it; bottles that warm up keep fermenting. That's why every batch is tested and every bottle says to keep it refrigerated.

Get the calculator

Download the kombucha scaling calculator. Two sheets: scale the recipe, where you type each ingredient's percentage and cost a pound and the raw mix you want, and each ingredient's weight for the run fills in, with the fermenters, what comes out after the fermentation loss, the bottles it fills and the cost of each bottle; and weigh the loss, where what went in and came out over a few batches gives your average fermentation loss. It's an ordinary Excel file with no macros, and it works in Google Sheets, LibreOffice and Numbers.

Where this stops working

Four flavors, a fermenter turning over every two weeks, kegs out at cafés, and a lab report for every batch. A sheet can say how much sugar a batch needs, but not which batch is in which keg, what each batch tested, or which bottles are near their date.

How TaroStack does it

TaroStack keeps the recipe by weight, takes each batch's ingredients off stock and checks its yield.

The recipe in the units you use. A recipe holds each ingredient by weight, with sugar bought by the 50-pound sack and used by the pound, and the cost of every bottle comes from what you paid. "What could I make right now" says how many runs the tea, sugar and fruit purée on the shelf allow.

Each run a batch. A run takes its ingredients off stock, records the lots of tea and fruit purée it used, and gets a lot of its own for the bottles, with how much came out good, how much was rejected and the labor minutes.

Yield checked from history. From your own batch history, TaroStack says whether a recipe yields what it claims and which ingredient's quantity is off, so a fermentation loss that creeps up shows in the numbers. A batch that tested high is an adjustment with its reason, spoiled, and shows in the waste report.

Recipes, batches, lots and yield are on every plan, from $49 a month. The first 30 days are free, with no credit card. If you'd like a hand setting up, ask, and we'll do it with you.

Questions people also ask

How much sugar do you need for 5 gallons of kombucha?

In the example, about 5.6% of the batch by weight: roughly 2.3 pounds of sugar for 5 gallons.

How much starter tea do you need for a big batch?

In the example, a tenth of the batch, saved from the last one.

How long does kombucha ferment in a large fermenter?

In the example, 7 to 14 days at about 75 to 80°F, until the taste and pH are where you want them.

How much does it cost to make kombucha in bulk?

In the example, $1.53 a 16-ounce bottle from a 50-gallon fermenter, against $4.23 in a kitchen batch.