Sourdough Hydration Calculator

What is dough hydration?

Hydration is the weight of water in a dough expressed as a percentage of the weight of flour. Mix 500 g of flour with 350 g of water and you have a 70% hydration dough. Bakers use this convention — baker’s percentages, where flour is always 100% — because it makes recipes scalable: the ratio describes the dough no matter how big the batch is.

Why the starter changes the number

A sourdough starter is itself made of flour and water, so it has to be counted. A starter kept at 100% hydration is half flour and half water by weight: add 100 g of it to your dough and you have really added 50 g of flour and 50 g of water. Ignore that and your “70% dough” can be several points wetter or drier than you think — which is exactly why two bakers following the same recipe sometimes end up with very different doughs. This calculator folds the starter into the totals for you.

What hydration should I aim for?

There is no single right answer, but the ranges are well established. Around 60–68% gives a firm, forgiving dough that is easy to shape — the best place to learn. 70–75% is the classic sourdough range, balancing an open crumb with manageable handling. Above 78% the dough turns slack and sticky and rewards experience with coil folds and gentle shaping.

Flour matters as much as the number: wholegrain and strong bread flours absorb far more water than plain white flour, so an 80% wholemeal dough can feel drier than a 72% white one. Treat the percentage as a starting point, adjust by feel, and keep notes on what each flour can take.