Sourdough hydration calculator
Count the flour and water in your starter as well as the ingredients added to the final dough.
How to use the result
Starter flour = starter weight ÷ (1 + starter hydration ÷ 100). Starter water is the remaining weight. Add those components to the final-dough flour and water; divide total water by total flour and multiply by 100.
Worked example
500 g flour + 350 g water + 100 g starter at 100% hydration → 550 g total flour, 400 g total water, 72.73% hydration.
Before changing the recipe
Enter the hydration of the starter actually used. Feeding ratio and starter hydration are different. This tool counts declared flour and water only; it does not estimate the moisture inside eggs, milk, fruit, or butter. For multiple preferments, calculate their components separately and combine them before entering the totals. It does not predict fermentation time or whether a dough will be easy to handle.
Reference: King Arthur Baking: bread hydration · Accessed October 6, 2026.
Calculation tool · Editorial review pending