Free Sourdough Starter Feeding Calculator
Calculate precise feeding weights in grams, tailor hydration percentages, and predict peak fermentation timing by room temperature.
🥖 Feeding Ratio & Yield Target
📊 Feeding Formula & Peak Window
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Mastering Sourdough Starter Ratios
A sourdough starter is a symbiotic culture of wild yeasts (primarily Kazachstania exigua and Candida humilis) and lactic acid bacteria (such as Fructilactobacillus sanfranciscensis). Feeding ratios control the rate of carbohydrate depletion and fermentation timeline.
How Feeding Ratios Scale Timeline
| Ratio (S:F:W) | Food Inoculation | Rise Time @ 24°C (75°F) | Best Use Case |
|---|---|---|---|
| 1 : 1 : 1 | 33% Starter | 3 – 4 Hours | Urgent same-day morning baking |
| 1 : 2 : 2 | 20% Starter | 5 – 6 Hours | Standard daytime maintenance / weekend baking |
| 1 : 4 : 4 | 11% Starter | 8 – 10 Hours | Overnight build before breakfast autolyse |
| 1 : 5 : 5 | 9% Starter | 10 – 13 Hours | Long slow cool overnight or hot summer climates |
Frequently Asked Questions
How do I know my starter is at its true peak?
At peak, the starter surface transforms from convex/domed to flat, filled with small popped gas bubbles, before just beginning to slightly dip in the center. It will float effortlessly in a cup of water (float test) and smell pleasantly fruity, alcoholic, and yogurty, rather than sharp vinegar.
Why does adding rye flour dramatically accelerate the rise?
Rye flour is packed with free simple sugars (fructose, glucose) and high amylase enzymatic activity that immediately feeds wild yeast populations without waiting for starches to break down. Even adding 15% to 20% dark rye into your feeding blend cuts peak time by up to 25%.
What water temperature should I use for sourdough feeding?
Ideal fermentation occurs between 24°C and 27°C (75°F to 80°F). If your kitchen is cool (18°C / 65°F), feeding with warm water around 28°C to 30°C (82°F to 86°F) gives the microbial colony an immediate metabolic head start.