When a recipe says “75% hydration,” it's telling you how wet the dough is — and from that one number an experienced baker can guess the crumb, the handling, and how the dough will feel. It's the single most useful number in bread baking, and it's trivial to calculate.
The hydration formula
Hydration is the weight of water as a percentage of the weight of flour. That's the whole definition:
So 1000 g flour with 750 g water is 75% hydration. Because it's a ratio, you can solve for any of the three: known flour and target hydration give you the water (flour × hydration); known water and flour give you the hydration.
What different hydration levels feel like
Higher hydration generally means a more open, airy crumb but a stickier, harder-to-handle dough. Lower hydration is easier to shape but tighter. Rough ranges:
| Hydration | Typical bread | Feel |
|---|---|---|
| ~60–65% | Sandwich / pan loaf, bagels | Stiff, easy to handle |
| ~65–70% | Standard sourdough, baguette | Workable, slightly tacky |
| ~75–80% | Rustic sourdough, ciabatta | Wet, slack, open crumb |
| 80%+ | Ciabatta, focaccia | Very wet, needs gentle handling |
The levain twist (true hydration)
Here's the part most hydration calculators skip. In a sourdough, your starter is itself flour and water — so the hydration figure written in the recipe isn't the bread's true hydration. To get the real number, you fold the starter's flour and water into the totals.
A 100%-hydration starter is half flour, half water by weight. So if a recipe uses 200 g of such starter, that's 100 g flour and 100 g water you need to add to your totals before calculating. Skip this and your “70%” dough might really be running at 72–73%.
Sources and method: see our methodology and references.