Kombucha Recipe Ratio Calculator

A Kombucha Recipe Ratio Calculator determines the exact amounts of tea, sugar, water, and starter tea needed for any batch size of homemade kombucha. Getting these ratios right is the single most important factor in producing safe, delicious fermented tea. The standard foundation is straightforward — 1 cup of sugar per gallon, 6-8 tea bags per gallon, and 10% mature kombucha as starter — but scaling these ratios accurately across different batch sizes and tea types requires careful calculation.

The calculator accounts for variations between tea types. Black tea uses fewer bags per gallon than white tea because of its higher tannin concentration. Green tea steeps at lower temperatures to avoid bitterness. Oolong falls in between. Each tea type also contributes different nutrients to the SCOBY (Symbiotic Culture of Bacteria and Yeast), affecting fermentation speed and flavor development. Understanding these differences helps brewers create consistent results across tea varieties.

Starter tea ratio is a critical safety parameter. The mature kombucha from a previous batch has a pH around 2.5-3.5, and adding 10-20% of this acidic liquid to your new sweet tea immediately lowers the pH below 4.5 — the threshold that prevents harmful bacteria and mold growth. Without enough starter, your brew is vulnerable during the first 24-48 hours before the SCOBY establishes active fermentation. This calculator ensures you never under-dose this essential ingredient.

Whether you are a beginner making your first 1-gallon batch or an experienced brewer scaling up to a 5-gallon continuous brew vessel, this calculator provides precise measurements tailored to your tea type, sugar preference, and batch size. It eliminates the guesswork from recipe scaling and helps maintain the consistency that produces reliable, great-tasting kombucha every time.

The core kombucha recipe follows established ratios validated by decades of home and commercial brewing:

For Jun tea (honey-based), the ratio shifts to 1 cup raw honey per gallon with green tea at 4 teaspoons per gallon. Jun cultures ferment faster than regular kombucha and prefer cooler temperatures (65-70°F vs 72-80°F), so the honey is added after the tea cools below 110°F to preserve its beneficial enzymes.

• First-time brewing: Get exact measurements for your starter kit or first batch without guesswork
• Batch scaling: Accurately scale a proven 1-gallon recipe up to a 5-gallon vessel or down to a quart jar
• Tea type experiments: Calculate correct ratios when switching from black tea to green, oolong, or white
• Continuous brew refills: Determine the right sweet tea recipe when harvesting and refilling your vessel
• Jun tea brewing: Get honey-to-green-tea ratios for the specialized Jun culture
• Teaching and workshops: Provide students with precise recipes for any batch size during brewing classes
• Quality control: Maintain consistent ratios across batches for reproducible flavor and fermentation

• Always cool sweet tea below 85°F before adding your SCOBY and starter tea
• Use filtered or dechlorinated water — chlorine kills beneficial bacteria
• Store extra starter tea in a glass jar at room temperature as backup
• If your starter tea is very sour (pH below 2.5), you can safely reduce to 8% starter
• Never use metal containers or utensils that contact the brew — glass, food-grade plastic, or ceramic only
• A healthy SCOBY should be at least 1/4 inch thick for reliable fermentation