Kombucha · Calculator

Kombucha Brewing Calculator

Dial in tea, sugar, starter liquid, and water for any batch size — plus a first-fermentation timing estimate from your room temperature.

Start calculating Read the guide
Tea, sugar, water and starter liquid prepared for a measured kombucha recipe

How to use this calculator

Plan the ingredients and timing for your first fermentation.

  1. 1

    Set the batch size. Enter your volume and choose litres or gallons.

  2. 2

    Choose your brewing settings. Set sugar and tea per litre, starter tea percentage and room temperature.

  3. 3

    Read your recipe. Use the sugar, tea, water and starter amounts, then follow the brewing steps and estimated fermentation window.

Keep per-litre amounts consistent when scaling. Tune one variable at a time and use your batch notes alongside the timing estimate.

Live calculator

Your brew

70g

About ⅓ cup of sugar per litre. Most brews use 60–80 g.

15%

Kombucha from your last batch. Use at least 10%; 15–20% protects a batch in a cool room.

g
°C

Your recipe · 1 L

Sugar · about ⅓ cup70g
Tea · 3 bags of 2 g6.0g
Water850 ml
Starter tea · 15%150 ml
First ferment · 24°C (75°F)7–10 days
Start tastingDay 7
See your 4 brewing steps

What to do next

Brew this batch in 4 steps

Every amount below is for your 1 L batch.

  1. 1

    Steep the tea

    10 min

    Heat 210 ml of the water. Steep 6.0 g of tea (3 bags) for 5–10 minutes, then take it out.

  2. 2

    Dissolve the sugar

    5 min

    Stir in 70 g of sugar until it disappears. Add the other 640 ml of cold water.

  3. 3

    Add the starter

    Once cool

    When it is below 30°C, pour in 150 ml of starter tea and add the SCOBY. Cover with a cloth.

  4. 4

    Let it ferment

    7–10 days

    Leave it somewhere around 24°C, out of the sun. Start tasting on day 7.

Free printable

Keep this batch on one page

A batch card made from your numbers, to save as a PDF or receive by email:

  • Your sugar, tea, water and starter in big type
  • These 4 steps with tick-boxes
  • Brew, start-tasting and bottle-by dates
  • A tasting log: sweet to sour, and pH

Optional. You can get your PDF without subscribing. Privacy notice.

Keep the per-litre amounts the same when you scale up. Timing is an estimate: taste and pH matter more than the exact day count.

Kombucha brewing guide

Dial the base recipe before chasing flavor.

Use the calculator for exact ingredient amounts, then set sugar, starter, and timing decisions in the right order for repeatable first fermentation.

Set sugar and starter first, then let temperature estimate your 1F window. Adjust live below.

How we calculate: Kombucha methods

Use these reference values to interpret your results

  • Sugar range

    55–85

    Grams per liter — a practical starting band for first fermentation.

  • Starter range

    10–20%

    Use enough acidic starter tea to protect the batch early.

  • 1F window

    5–14 d

    Timing shifts with temperature, sugar load, and starter strength.

Base ratio formula

g per liter × batch liters

Keep per-liter values constant when scaling. If your sugar target is 70 g/L and your batch is 3 L, total sugar is 210 g.

Use sugar as your primary fermentation dial

Higher sugar inputs usually extend the tasting window and leave more room for acidity development over time.

Lower sugar batches can finish faster and taste drier, so measure consistently and adjust in small steps.

Starter percentage controls risk and speed

Using enough acidic starter tea lowers pH early, which protects your batch and helps the culture take over quickly.

When room temperature is cooler, a slightly higher starter percentage can help keep fermentation moving steadily.

Use temperature to estimate 1F timing

Warmer rooms ferment faster and can overshoot acidity quickly. Cooler rooms slow fermentation and usually need longer windows.

Taste checkpoints matter more than exact day counts, so use timing as a guide, not an absolute.

Estimated 1F window by temperature

≤ 20°C → 10–14 days
21–23°C → 8–12 days
24–25°C → 7–10 days
≥ 26°C → 5–8 days

Keep ratios stable when scaling

When moving from small to larger batches, keep tea, sugar, and starter ratios consistent first.

Then adjust based on taste and pH logs so your process stays predictable from batch to batch.

Safety checks before bottling

Taste for balance and verify your batch is clearly acidic before moving to second fermentation.

If a batch smells off, shows dry fuzzy growth, or lacks acidity, discard it and restart with fresh starter tea.

FAQ

Kombucha brewing questions

Common questions about sugar, starter, tea, and timing.

How much sugar per liter for kombucha?
Most brewers use about 55 to 85 g/L depending on target dryness and fermentation length.
How much starter tea should I use?
A common range is 10% to 20% of total batch volume, with 15% as a dependable baseline.
How long does first fermentation take?
Usually 5 to 14 days depending on temperature, starter strength, and sugar concentration.
Can I brew with green tea only?
Yes, but many brewers blend black and green tea for stronger SCOBY performance and balanced flavor.

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Calculators and guides for your next step.

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