🍞 Baking
Sourdough Hydration Calculator
Work out true hydration including the starter, plus salt percentage and dough weight. Enter your formula, then press Calculate.
About the Sourdough Hydration Calculator
A sourdough formula lists flour and water, but the starter contains both. If you add 100 g of 100%-hydration starter, you are adding 50 g flour and 50 g water, not 100 g of either. Ignoring that makes the dough seem wetter or drier than the true hydration.
This calculator splits the starter into its flour and water, adds them to the main flour and water, and reports total hydration, salt percentage and dough weight. A 500 g flour / 350 g water dough with 100 g of 100% starter is 400 g total water over 550 g total flour — 72.7%, not 70%.
How the calculation works
- Starter flour = starter ÷ (1 + starter hydration ÷ 100).
- Starter water = starter − starter flour.
- True hydration = (water + starter water) ÷ (flour + starter flour) × 100.
- Salt % = salt ÷ total flour × 100.
Reference values
| Hydration | Feel | Typical use |
|---|---|---|
| 60–65% | Firm, easy to shape | Bagels, dense rye |
| 65–70% | Moderate | Everyday country loaf |
| 70–75% | Soft, extensible | Open-crumb bread |
| 75–80% | Slack | High-hydration artisan |
| 80%+ | Very wet | Advanced handling |
Worked example: two starters, two hydrations
A dough with 500 g flour, 350 g water and 100 g of 100%-hydration starter has 550 g total flour and 400 g total water: 72.7% hydration. If the same 100 g starter is 50% hydration, it adds 66.7 g flour and 33.3 g water, giving 566.7 g flour and 383.3 g water—67.6%, a very different dough from the same ingredient list.
That is why a recipe that says “100 g starter” without stating its hydration is incomplete. Ask for the starter hydration, or weigh the flour and water in the starter separately. Once the totals are known, the percentage is unambiguous and the dough can be repeated.
Why flour absorption varies
Hydration is a ratio, but the dough's behaviour depends on the flour. Wholemeal flour absorbs more water than white flour because the bran and germ bind it, so a 75% wholemeal dough feels stiffer than a 75% white one. Strong bread flour with high protein also takes more water than a soft pastry flour, and aged flour hydrates differently from fresh.
That is why recipes give a hydration range and a description of the dough rather than a single number. Start at the lower end, mix, and add water once the flour is fully hydrated — usually after a 20–30 minute rest. Judging by feel at that point is more reliable than chasing a percentage that was written for a different flour.
Frequently asked questions
Hydration table for 1 kg of flour
Hydration is water weight divided by flour weight, so the table scales linearly. A 20 percent starter at 100 percent hydration adds its own flour and water, which is why the dough feels wetter than the headline figure.
| Hydration | Water for 1 kg flour | Total before starter | Bakers % |
|---|---|---|---|
| 60% | 600 g | 1600 g | 60% |
| 65% | 650 g | 1650 g | 65% |
| 70% | 700 g | 1700 g | 70% |
| 75% | 750 g | 1750 g | 75% |
| 80% | 800 g | 1800 g | 80% |
| 85% | 850 g | 1850 g | 85% |
Below 65 percent the dough is stiff and suits bagels and pizza; 70 to 78 percent is the everyday sandwich-loaf range; above 82 percent the dough needs folds rather than kneading to hold its shape. Ambient temperature shifts the feel by roughly the same amount as five percentage points of water.