Calculate sourdough bread recipes with starter, levain, hydration, and timing. Scale for any loaf size with precise baker's percentages and fermentation schedules.
Sourdough baking is both art and science — and the science requires math. Between the starter, the levain, the autolyse, and the final dough, there are multiple stages where flour and water enter the recipe. Tracking the true hydration and baker's percentages across all these stages is critical for consistent results. This Sourdough Calculator handles the math so you can focus on feel and timing.
The calculator accounts for the flour and water already present in your sourdough starter. If your levain is 100% hydration (equal parts flour and water by weight), then 200g of levain contributes 100g flour and 100g water to your final dough. Ignoring this is the #1 reason home sourdough bakers get inconsistent hydration. A recipe targeting 75% hydration that ignores the levain's water might actually be running at 80%.
Enter your target loaf weight, desired hydration, and starter details. The calculator outputs exact weights for every stage: feeding your starter, building the levain, mixing the dough, and the final formula with true baker's percentages. It also suggests fermentation timing based on your kitchen temperature.
Sourdough has more variables than any other bread. This calculator tracks flour and water from the starter through the final dough to give you true hydration and precise weights at every stage. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation.
Total Flour = Total Dough Weight ÷ (1 + Hydration% + Levain% × Starter Hydration Factor + Salt%). Levain Flour = Total Flour × Levain%. Levain Water = Levain Flour × Starter Hydration. Final Flour = Total Flour - Levain Flour. Final Water = (Total Flour × Hydration%) - Levain Water.
Result: Final: 407g flour, 339g water, 102g levain, 10g salt
For a 900g loaf at 75% hydration with 20% levain (100% hydration starter): total flour is 509g, levain contributes 51g flour + 51g water, so final mix needs 458g flour and 331g water plus 10g salt.
True hydration in sourdough includes ALL water from every source: the main water addition, the water in the levain, and even liquid milk or eggs if used. A recipe that says "75% hydration" should mean 75% total water relative to total flour — including what's inside the starter. Many online recipes ignore this, leading to confusion when results vary.
Temperature is the master control for sourdough fermentation. At 68°F, expect 6–8 hours for bulk fermentation. At 78°F, it might only need 3–4 hours. The dough should increase in volume by 50–75% and feel airy and jiggly. Use a clear container with a rubber band to track rise.
Plan backwards from when you want to bake. If baking at 10am, mix your levain at 10pm the night before (12-hour levain at 68°F). Or mix at 6am for a same-day bake with a fast 4-hour levain at 78°F. Adjust timing rather than amount of starter for schedule flexibility.
Beginners should start at 70–72%. Intermediate bakers can try 75%. Advanced bakers work with 78–85% for open crumb artisan loaves.
Typically 15–25% of total flour weight. Less levain (10–15%) gives longer, more complex fermentation. More (25–30%) speeds things up.
Yes! A 100% hydration starter is half flour, half water. A stiff starter (60%) contributes more flour and less water. The calculator accounts for this.
At 75°F, about 4–6 hours or until the dough has risen 50–75%. Colder kitchens need longer. Warmer kitchens are faster.
Yes — after shaping, refrigerate at 38–42°F for 12–72 hours. This develops complex flavor without over-fermenting.
Over-fermentation or too much starter. Reduce levain percentage, use younger (just-peaked) starter, and shorten bulk fermentation slightly.