Dough Hydration, Explained

Hydration is the amount of water in a dough relative to the flour, written as a percentage. It’s one of the most useful single numbers in baking because it predicts how a dough will feel, how open the crumb can get, and how forgiving the dough is to shape.

How to calculate hydration

Hydration is water weight divided by flour weight, times 100:

hydration % = (water ÷ flour) × 100

For example, 1000 g of flour with 750 g of water is 75% hydration. The math is always by weight, not volume, which is why a kitchen scale matters more than measuring cups for repeatable bread.

If you use a sourdough starter or levain, remember it contains both flour and water — usually in equal parts at 100% hydration. To be precise, the flour and water inside the levain should be counted toward your totals. This is the kind of bookkeeping a tool like Sourdough Journal handles automatically so the percentages stay honest.

What hydration changes

• Lower hydration (around 60–68%) — stiffer, easier to shape, tighter crumb. Good for sandwich loaves, bagels, and beginners building confidence.
• Mid hydration (around 70–75%) — the common range for a rustic sourdough boule: workable by hand, with a reasonably open crumb.
• Higher hydration (78%+) — slacker, stickier dough that can produce a very open, custardy crumb, but demands gentler handling and stronger flour.

Higher isn’t “better.” The right hydration depends on your flour’s protein, your shaping skill, and the bread you actually want.

Adjusting hydration without starting over

Because hydration is a ratio, you can nudge it. To raise hydration, add water in small increments (a few percent at a time) and let the dough absorb it before deciding. To lower it, increase flour slightly. Change one variable per bake and write down what happened — see baker’s percentage for the language that makes those adjustments repeatable, and starter care for keeping the levain side of the equation predictable.