Kombucha · Calculator

Kombucha Batch Calculator

Scale any kombucha recipe from 1L to 25L while tea, sugar, and starter stay perfectly proportional — no guesswork, no weak batches.

Start calculating Read the guide
Different-sized kombucha jars beside proportioned tea, sugar and starter liquid

How to use this calculator

Scale a kombucha recipe with consistent ingredient ratios.

  1. 1

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

  2. 2

    Choose your ingredient ratios. Select the sugar profile and set the starter liquid percentage.

  3. 3

    Read the batch amounts. Weigh the sugar and tea and measure the water and starter shown for your target volume.

Keep per-litre ingredient loads consistent when moving between batch sizes, then refine from your brewing notes.

Live calculator · updates as you type

Your batch

L
Volume unit
Sugar profile
15%

Your recipe

Sugar 350g
Tea 30.0g
Tea bags (2 g)15
Starter liquid750 ml
Top-up water4250 ml
Total volume5.00 L
Tea concentration 6 g/L
See your 4 brewing steps

What to do next

Brew this batch in 4 steps

Every amount below is for your 5 L batch.

  1. 1

    Steep the tea

    10 min

    Heat 1.06 L of the water. Steep 30.0 g of tea (15 bags) for 5–10 minutes, then take it out.

  2. 2

    Dissolve the sugar

    5 min

    Stir in 350 g of sugar (about 1¾ cups). Add the other 3.19 L of cold water.

  3. 3

    Add the starter

    Once cool

    Below 30°C, pour in 750 ml of starter tea and add the SCOBY. Cover with a cloth.

  4. 4

    Let it ferment

    7–12 days

    Keep it at 21–25°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 amounts in big type
  • These steps with tick-boxes
  • Brew, taste and bottle dates
  • A tasting log: sweet to sour, and pH

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

Use this as a baseline recipe calculator. Fermentation speed and acidity still depend on SCOBY strength, temperature, and oxygen exposure during first fermentation.

Batch scaling guide

Scale with control, not trial and error.

Use the calculator for exact scaling math, then use these process checkpoints to keep taste and fermentation behavior stable as your batches grow.

Multiply each per-liter value by your batch size to scale cleanly. Adjust live below.

How we calculate: Kombucha methods

Use these reference values to interpret your results

  • Scaling range

    1–25 L

    Maintain per-liter math so each step-up keeps the same balance.

  • Core rule

    Ratio lock

    Tea, sugar, and starter stay proportional during scaling.

  • Best practice

    Log runs

    Process notes catch drift faster than memory-based tweaks.

Scaling formula

per-liter × total liters

Keep this constant across every ingredient. If your tea load is 6 g/L and the batch is 8 L, total tea is 48 g.

Lock your baseline recipe first

Validate one reliable small batch before scaling so you are multiplying a known-good process.

If the baseline is unstable, scaling amplifies the same issues.

Batch size changes fermentation behavior

Larger batches usually have slower thermal swings and can ferment slightly differently than 1L test runs.

Use the calculator as baseline math, then verify with taste and acidity checkpoints.

Keep starter percentage consistent

Starter ratio is part of the scaling math, not an afterthought. Keep it proportional to total volume.

Adjust only when needed for temperature or acidity control, and document the change.

Track every scaled run

Record room temperature, start pH, sugar profile, and day-by-day tasting notes.

Small process logs make later scaling decisions much more reliable.

Use quality checkpoints at each size jump

Move up in steps, not huge jumps. Confirm taste, acidity, and timing at each new batch size.

When output drifts, troubleshoot process variables before changing your core ratio model.

TasteBalanced, clearly acidic, no off or solvent notes before scaling further.
AcidityStart pH low enough that the culture dominates within the first day or two.
Timing1F window lands in the same range you saw at the previous batch size.
Step sizeDouble at most per jump (1L to 2L to 4L) so drift stays traceable.

FAQ

Kombucha batch-scaling questions

Common questions about scaling tea, sugar, and starter together.

Can I scale kombucha recipes directly?
Yes, as long as tea, sugar, and starter ratios stay proportional to the total volume.
Why does large-batch kombucha taste different?
Thermal behavior and oxygen exposure can shift fermentation speed even when recipe math is identical.
What starter ratio is safe for scaling?
Around 15% is a solid default, with range adjustments based on acidity and ambient temperature.
Should I change tea strength when scaling?
Keep tea concentration steady first, then tune only after tasting the scaled result.

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Calculators and guides for your next step.

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