This tool helps home brewers calculate precise ingredient ratios for kombucha batches. Adjust measurements for different batch sizes, tea types, and sugar preferences. Get accurate ratios to avoid over- or under-fermenting your homemade kombucha.
How to Use This Tool
Start by entering your desired total kombucha batch size and selecting the corresponding volume unit (liters or gallons). Choose your tea type from the dropdown, then select how you measure tea (grams, tea bags, or tablespoons). Next, pick your sugar type and preferred measurement unit for sugar. Adjust the starter tea percentage between 5% and 20%: 5% produces milder kombucha, 20% yields a tarter batch. Click Calculate to see your precise ingredient ratios, or Reset to clear all inputs.
Formula and Logic
All calculations use liters and grams as base units, then convert back to your selected units for readability. The core logic follows standard home brewing guidelines:
- Batch Volume Conversion: Convert user-selected batch size to liters using standard volume conversion factors (1 US gallon = 3.78541 L, 1 UK gallon = 4.54609 L).
- Starter Tea Volume: Calculate as (starter percentage / 100) * total batch volume in liters. Starter tea is subtracted from total batch volume to get the sweet tea volume (water, tea, and sugar before adding starter).
- Tea Amount: Multiply sweet tea volume in liters by a tea-type specific ratio (black/oolong: 6g/L, green:5g/L, white:4g/L, herbal:8g/L). Convert to your selected tea measurement unit (1 tea bag = 2g, 1 tbsp loose leaf = 2g).
- Sugar Amount: Multiply sweet tea volume in liters by 60g/L (standard ratio for balanced sweetness). Convert to your selected sugar measurement unit (1 cup = 200g, 1 oz = 28.35g).
Practical Notes
Adjust these ratios based on real-world home brewing experience:
- Herbal (caffeine-free) teas lack the caffeine SCOBYs need to thrive: add an extra 5% starter tea if using herbal tea.
- Raw, brown, and coconut sugars are less sweet than white granulated sugar: increase sugar by 5-10% if you prefer a less tart final product.
- Steep tea for 10-15 minutes maximum: over-steeping leads to bitter kombucha. Let sweet tea cool to room temperature before adding starter tea to avoid killing the SCOBY.
- Store starter tea in a clean glass jar at room temperature: use starter tea from a previous batch that is less than 2 weeks old for best results.
- 1 gallon of kombucha yields approximately 16 8oz servings, so scale batch size to your household's consumption.
Why This Tool Is Useful
Home kombucha brewing requires precise ratios to avoid mold growth, over-fermentation, or bland flavor. This tool eliminates guesswork for new and experienced brewers alike: it adjusts for batch size, tea type, and sugar preferences, so you don't have to do manual unit conversions or memorize ratios. It saves time on calculation, reduces ingredient waste from incorrect measurements, and helps you consistently produce high-quality kombucha at home.
Frequently Asked Questions
Can I use honey instead of sugar for kombucha?
We do not recommend honey for first-time brewers: honey has natural antimicrobial properties that can slow SCOBY growth, and it produces a distinct flavor that may not appeal to all drinkers. If you choose to use honey, increase the starter tea percentage to 15% to support fermentation.
What happens if I use too little starter tea?
Starter tea lowers the pH of the batch to prevent mold growth. Using less than 5% starter tea increases the risk of mold, off-flavors, and failed fermentation. Always use at least 5% starter tea from a healthy, active batch.
How do I adjust ratios for a second fermentation (fizz)?
This tool calculates ratios for the first fermentation (F1) only. For second fermentation (F2, adding flavor and fizz), use 16-24 oz glass bottles, add 1-2 tsp fruit juice or sugar per bottle, and let ferment at room temperature for 2-3 days before refrigerating.
Additional Guidance
Always use non-reactive containers (glass, food-grade plastic) for brewing: metal can react with the acidic kombucha and damage your SCOBY. Keep your brewing vessel out of direct sunlight, as UV light can harm the SCOBY. If you notice mold (fuzzy blue, green, or black spots) on your SCOBY, discard the entire batch immediately and sanitize all equipment before starting a new batch. For consistent results, use the same tea and sugar type for 3-4 batches before experimenting with new ingredients.