How sourdough hydration works
Hydration is the weight of water divided by the weight of flour, written as a percentage. A dough with 500 g flour and 375 g water is 75% hydration. Bakers use it because it tells you how a dough will feel before you mix it, whatever the batch size.
Sourdough adds one wrinkle: the starter is made of flour and water too. A typical recipe with 450 g flour, 330 g water and 100 g of 100% hydration starter looks like 73% hydration if you ignore the starter. Count its 50 g of flour and 50 g of water, and the dough is really 76%. That difference is why the same “75%” dough can feel wetter in one recipe than another.
The formula
True hydration = (water + water in starter) ÷ (flour + flour in starter) × 100
For a starter at 100% hydration, half its weight is flour and half is water. For other starters, flour in starter = starter weight ÷ (1 + starter hydration ÷ 100), and the rest is water. The calculator handles this for you when you change the starter hydration.
Sourdough hydration chart
| Hydration | Dough feel | Crumb you can expect |
|---|---|---|
| 60 to 65% | Firm and smooth, like play dough | Tight and even. Good for sandwich loaves and bagels |
| 65 to 70% | Soft, a little tacky | Moderately open. A very forgiving place to start |
| 70 to 75% | Soft and sticky, relaxes on the bench | Open and airy in a well-fermented loaf |
| 75 to 80% | Sticky and slack, wants wet hands | Open, glossy crumb with larger holes |
| 80 to 90% | Very wet, almost pourable at first | Wide open. Ciabatta and focaccia territory |
Flour changes everything in this table. Strong bread flour holds more water than all-purpose flour, and whole grain flours absorb more again. If a dough feels much wetter than you expected, try 3 to 5% less water next time rather than adding flour during mixing.
Raising hydration step by step
- Increase by 2 to 3% at a time, not 10% at once.
- Hold back some water and add it after the first mix, once the dough has some strength.
- Wet your hands, not the bench, when you fold and shape a sticky dough.
- Give wetter doughs an extra set of stretch and folds during bulk.
Building a recipe from scratch? The sourdough calculator works the other way round: choose a hydration and loaf size, and it gives you every ingredient. To see your recipe as percentages, use the baker's percentage calculator.
