Free Sourdough Starter Feeding Calculator
Calculate precise flour, water, and carryover starter weights for any feeding ratio (1:1:1 to 1:5:5) and predict hours until peak leavening rise.
🥖 Feeding Ratio & Batch Target
📊 Scale Recipe & Peak Schedule
Recommended Tools & Equipment
Tested hardware and components for high reliability
Sourdough Starter Inoculation Ratios & Fermentation Kinetics
A healthy sourdough starter is a symbiotic culture of wild yeasts (predominantly Kazachstania exigua and Candida humilis) and lactic acid bacteria (such as Fructilactobacillus sanfranciscensis). How quickly your starter doubles or triples in volume is not fixed; it is completely determined by two levers: feeding inoculation ratio and ambient proofing temperature.
1. Choosing the Right Feeding Ratio
- 1:1:1 Ratio (Fast Sprint): 1 part starter, 1 part flour, 1 part water. High microbial population density. Peaks rapidly in 3.5 to 5 hours. Best for same-day baking when you want to start mixing dough by early afternoon.
- 1:2:2 Ratio (Standard Refreshment): Moderate microbial buffer. Reaches peak in 5 to 7 hours at room temperature. Great for maintaining active counter starters.
- 1:4:4 to 1:5:5 Ratio (Overnight / Warm Room): High food dilution. Because yeasts have 4× to 5× more fresh flour sugars to consume, acidification is delayed, and peak rise takes 10 to 14 hours. Perfect for feeding at 10 PM to mix dough at 8 AM.
2. The Crucial "Dome Peak" Window
You should mix your leaven into dough when the starter is at its maximum convex dome, just before the surface flattens or starts to collapse. At this peak point, yeast population and active carbon dioxide gas production are maximized, while gluten-degrading proteolytic enzymes have not yet destroyed the structure.
Frequently Asked Questions
How does whole wheat or rye flour affect the rise time?
Whole grain flours (especially dark rye and whole wheat) contain the grain's bran and germ, providing rich minerals, ash, and native enzymes that accelerate fermentation by 25% to 35% compared to refined white flour. When feeding 100% rye, expect the starter to peak 1 to 2 hours sooner.
What is the "float test" and is it reliable?
The float test involves dropping a teaspoon of starter into water. If it floats, it has trapped enough CO2 gas bubbles to be less dense than water. While useful for white flour starters, whole wheat or high-hydration 100% rye starters often fail to float despite being perfectly active due to weak gluten trapping.
Why does a hungry starter produce a dark liquid (hooch) on top?
Hooch is an alcohol byproduct produced when wild yeasts exhaust all available carbohydrates in the flour. Hooch is harmless and signals extreme hunger. Simply pour it off (or stir it back in for extra sourness) and feed with a generous 1:3:3 or 1:5:5 ratio.
How does temperature affect lactic vs acetic acid flavor?
Cooler fermentation (60-68°F / 15-20°C) favors acetic acid production (sharp, tangy, vinegar-like notes). Warmer fermentation (78-85°F / 25-29°C) encourages lactic acid bacteria to produce lactic acid, resulting in a gentle, creamy, yogurt-like sourness.