How this calculator works
Baker's percentages express every ingredient against total flour. The levain is split into its flour and water parts first: levainFlour = grams ÷ (1 + hydration/100), water is the rest. Total flour is dough flour plus levain flour; total water likewise. Hydration is total water ÷ total flour. Salt is a percentage of total flour.
"How much water" mode does the same in reverse: total flour × target ÷ 100, minus the water the levain already carries.
Sources
Formulas copied from Banneton's BakersMath (Models.swift) on September 17, 2026: hydration, water(forFlour:targetHydration:), levainSplit, and totalHydration. The multi-flour version, which splits flour into two types, is in the app's advanced calculator.
Questions
What is sourdough hydration?
Water weight divided by flour weight, as a percentage. 350 g water on 500 g flour is 70% hydration. Higher hydration gives a more open crumb but a slacker, harder-to-shape dough.
Does the levain count toward hydration?
Yes. A 100%-hydration levain is half flour, half water by weight, so 100 g of it adds 50 g flour and 50 g water to the totals. Leaving it out is the most common reason a recipe's stated hydration doesn't match the dough in the bowl.
What hydration is good for a beginner?
Around 65 to 72% is forgiving to shape and still gives a good crumb. Many popular country loaves sit at 75 to 78%. Whole grain and rye flours absorb more water, so the same percentage feels drier.
How much salt goes in sourdough?
About 2% of total flour weight is standard. For 600 g total flour that's 12 g. The calculator uses total flour including the flour inside the levain, which is how baker's percentages are defined.
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