If you understand baker's percentages, you already know what hydration is in formal terms: it's the weight of water expressed as a percentage of the weight of flour. But the formal definition undersells it. Hydration is the single variable that changes how a dough behaves more than any other. Same flour, same salt, same yeast: change only the hydration and you have a different dough.
The number itself
hydration % = (water weight / flour weight) × 100
Hydration is just water-to-flour expressed as a percentage.
If a dough uses 1000 g of flour and 650 g of water, that's 65% hydration. If a dough uses 500 g of flour and 425 g of water, that's 85% hydration. The number tells you nothing about how big the batch is, only about the ratio.
If the recipe contains other liquid ingredients (milk, eggs, oil, honey), convention is to count their water content too, but in practice most home bakers only count actual water. For a strict pizza or sourdough formula this is fine. For an enriched dough like brioche, the milk and eggs matter and a more careful calculation is needed (covered in the brioche article).
What hydration actually changes
More water in the dough has three direct effects.
- 1.The crumb gets more open. Higher hydration produces larger, more irregular air pockets in the finished bread. The bigger holes that bakers chase in a country sourdough come from high hydration combined with strong gluten and good shaping.
- 2.The dough gets harder to handle. A 60% dough you can knead by hand on a wooden board. An 85% dough sticks to everything, including itself, and needs stretch-and-fold technique instead of kneading. The difference is dramatic.
- 3.Fermentation accelerates. A wetter dough ferments faster at any given temperature because yeast and bacteria move more freely through it. This is why high-hydration sourdoughs need closer watching during bulk fermentation.
Where to put your dough on the hydration spectrum
These ranges are conventions, not rules. Each one assumes you're using bread flour or a strong all-purpose flour. Whole-grain flours absorb more water and shift everything up by 5–10%.
- 55–60%. Bagels, pretzels, some pasta doughs. Stiff, easy to shape, tight crumb.
- 60–65%. Neapolitan pizza dough, lean sandwich loaves. Easy to handle, even crumb.
- 65–72%. Most everyday bread, baguettes, ciabatta dough's lower end. The standard zone for home baking.
- 72–80%. Country sourdough, open-crumb hearth breads. Sticky but rewarding. Stretch and fold required.
- 80–90%+. Ciabatta, focaccia, some pizza in teglia styles. Slack to the point of being pourable. Different handling entirely, usually mixed in a bowl, never kneaded by hand.
Two doughs at the extremes
It's worth seeing the difference in concrete terms. Both of these doughs use the same flour, the same salt, and the same yeast, only the hydration differs.
Stiff dough (60% hydration)
Slack dough (85% hydration)
Difference: 125 g of water (roughly half a cup).
Same recipe, two hydrations. The slack version weighs only 14% more, but behaves entirely differently.
Why hydration is not just one number
Two doughs at the same listed hydration can behave very differently because of two factors that the percentage alone doesn't capture: flour absorption and temperature.
Flour absorption
Different flours hold different amounts of water. A high-protein bread flour absorbs more water than an all-purpose flour. A whole-wheat flour absorbs more than a refined white flour. A flour milled six months ago absorbs less than the same flour milled last week. Even within the same brand, lot-to-lot variation is real.
This means a 75% hydration dough made with one flour can feel like a 70% hydration dough made with a different flour. The number is a starting point, not an absolute. Experienced bakers learn to adjust based on how the dough looks and feels in the first few minutes of mixing.
Temperature
A warm dough feels slacker than a cold dough at the same hydration. As the dough cools (for instance, during a cold retard) it firms up and becomes easier to shape. As it warms, it relaxes. This is why bakers often shape their dough straight out of the fridge: the cold gives them an extra few percentage points of effective firmness to work with.
Practical advice for picking a hydration
If you're new to a particular bread, start at the lower end of its conventional range. A first attempt at country sourdough at 72% will be easier to handle than at 80%, even if the open-crumb instagram photos all use higher numbers. You can ladder up by 2–3% on each successive bake until you find the level you can manage.
If you're switching to a new flour, drop your hydration by 5% on the first try. If the dough feels too stiff once it's hydrated, add water in small amounts until it feels right. Note what you ended up with: that's your new baseline for that flour.
If your dough is consistently too slack to shape, the answer isn't always to lower hydration. Sometimes it's to develop more gluten through longer mixing, autolyse, or more stretch and folds. Strong gluten holds water that weak gluten can't.
The dough calculator's hydration slider lets you adjust hydration on a recipe and see all ingredient weights recalculate live. The recipe's notes field is the place to record what hydration actually worked for *your* flour. Lievanto preserves the formula's listed value but the cook session log is where you write what you ended up doing.
The mistake to avoid
Chasing high-hydration doughs because they look impressive online is the most common reason home bakers get frustrated. A well-made 70% sourdough is a better loaf than a poorly-handled 85% sourdough. Hydration is one variable among many. Get the others right (good flour, proper fermentation, careful shaping) before you push the water past what your skill and your kitchen allow.