What hydration actually means
Hydration is water as a percentage of flour, by weight. 500 g flour with 350 g water is 70% hydration. It is the single best predictor of how a dough behaves: how sticky it feels, how open the crumb bakes, how much strength you need to build during folds.
Why your starter changes the number
Starter is not a magic third ingredient — it is flour and water that happen to be fermenting. A typical starter is kept at 100% hydration: equal weights of both. So 100 g of it quietly adds 50 g flour and 50 g water to your dough.
Worked example — the classic beginner recipe:
- 500 g flour + 350 g water + 100 g starter (100%) + 10 g salt
- True flour = 500 + 50 = 550 g · true water = 350 + 50 = 400 g
- Hydration = 400 ÷ 550 = 72.7% — not the 70% the quick division suggests
That 2.7-point gap is the difference between a dough that behaves as the recipe author intended and one that feels mysteriously slack. Keeping a stiff starter (50–65% hydration) skews the numbers even further — which is exactly why the calculator asks for starter hydration.
Choosing a hydration
- 55–65% — stiff, easy to handle: bagels, pretzels, tight sandwich loaves.
- 65–70% — the beginner sweet spot: forgiving to shape, still nicely open.
- 70–78% — classic artisan range: slack, slightly sticky, big irregular crumb.
- 78–90% — expert territory: ciabatta and focaccia, wet hands mandatory.
Two caveats: flour matters (whole grain and high-protein flours drink more water, so 75% with strong bread flour can feel like 70% with plain flour), and climate matters a little too. Treat the ranges as a map, not a law.
Using the reverse mode
“Plan a dough” works backwards from the answer. Say you want two 900 g loaves at 75% hydration with 20% starter and 2% salt: the calculator splits the starter into its flour and water first, then hands you the exact weights to scale — flour 915 g, water 661 g, starter 203 g, salt 20 g. No algebra at midnight.
FAQ
Does starter count toward hydration?
Yes — always. It's flour and water like everything else in the bowl. See the worked example above.
What hydration should a beginner start with?
65–70%. Move up 2–3% per bake as your shaping improves.
Is 75% high?
Moderately. Expect a sticky, relaxed dough that wants wet hands and gentle handling — and pays you back with an open crumb.
How do I do this by hand?
Starter flour = starter ÷ (1 + hydration/100). Starter water = the rest. Add each to your flour and water, divide water by flour, multiply by 100.
I keep a stiff starter — does it matter?
Quite a lot. 150 g of a 50% starter is 100 g flour + 50 g water. Set “starter hydration” to your real number and the totals fix themselves.