Sourdough Ratio Calculator
The Sourdough Ratio Calculator computes precise ingredient amounts for sourdough bread based on your desired dough weight and hydration. Calculate starter percentage, pre-fermented flour, and adjust ratios for different sourdough styles — from tangy San Francisco to mild country loaves.
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What is a Sourdough Ratio?
Sourdough ratios express the proportion of sourdough starter relative to total flour, typically 15-30% of flour weight. A common ratio is 20% starter, 70% hydration, and 2% salt. The starter's own flour and water content must be factored into the total dough formula to maintain accurate hydration.
Sourdough starter itself has a ratio — typically 1:1:1 (equal parts starter, flour, water by weight at each feeding) or 1:5:5 for less frequent feedings. The starter ratio affects fermentation speed, flavor profile (acidity), and rise quality.
Formulas & Equations Used
This Sourdough Ratio Calculator uses the following core equations:
1 Starter Amount ▼
For 20% starter with 500g flour: Starter = 500 × 0.20 = 100g.
2 Adjusted Water (accounting for starter) ▼
Assuming 100% hydration starter: half is flour, half water. Subtract the starter's water contribution.
3 Total Dough Weight ▼
500g flour + 350g water + 100g starter + 10g salt = 960g total dough.
How to Use This Sourdough Ratio Calculator
Follow these 3 simple steps:
Enter Your Values
Type the known values into the input fields above. The Sourdough Ratio Calculator accepts any positive numbers.
Choose Calculation Mode
Select Solve, Simplify, or Scale mode in the calculator. Each applies different equations to your inputs.
View Results
Click Calculate to see your answer with a visual ratio bar, pie chart, and step-by-step solution breakdown.
Example Problems & Step-by-Step Solutions
Here are 3 worked examples using this Sourdough Ratio Calculator:
Example 1 Standard country loaf: 500g flour, 20% starter, 72% hydration
Example 2 High-hydration sourdough: 80% hydration, 25% starter
Example 3 Starter feeding ratio: 1:5:5
Frequently Asked Questions
What percentage of starter should I use? ▼
Standard sourdough uses 15-25% starter relative to total flour weight. Lower percentages (10-15%) produce milder flavor with longer fermentation. Higher percentages (25-30%) give tangier flavor and faster rise.
How does starter ratio affect sourdough flavor? ▼
More starter (25%+) speeds fermentation but produces more lactic acid (mild tang). Less starter (10-15%) with a longer cold ferment develops more acetic acid (sharp vinegar tang). Temperature also affects acid balance.
What is the ideal starter feeding ratio? ▼
For daily baking: 1:1:1 (equal parts starter, flour, water). For weekly baking: 1:5:5 or 1:10:10 before refrigeration. Higher ratios dilute acidity and give the starter more food, extending its peak window.
How do I calculate pre-fermented flour? ▼
Pre-fermented flour is the flour inside your starter. With 100% hydration starter, half is flour. If you use 100g starter, 50g is pre-fermented flour. Subtract this from your total flour to get the flour you actually add to the dough.
Can I use a different hydration starter in the same recipe? ▼
Yes, but adjust water accordingly. A 75% hydration starter has different flour/water proportions than 100%. For 100g of 75% starter: flour = 57g, water = 43g. Recalculate added flour and water.