Sourdough Hydration Calculator

How It Works

Baker's math expresses every ingredient as a percentage of total flour weight. Hydration is the ratio of total water to total flour in a dough — but when you use a sourdough starter, some of that flour and water is hidden inside the starter itself.

A 100% hydration starter is equal parts flour and water by weight. A stiff levain at 50% hydration contains twice as much flour as water. This calculator decomposes your starter into its flour and water components, adds them to the main recipe amounts, and gives you the true overall hydration.

Key concepts:

• Starter flour = starter weight ÷ (1 + hydration/100)
• Starter water = starter weight − starter flour
• Total hydration = (total water ÷ total flour) × 100
• Inoculation = starter flour ÷ main flour × 100 — controls fermentation speed

How to Use

1. Enter main flour weight — the flour you add directly to the dough (not what's in the starter)
2. Enter main water weight — water added directly to the dough
3. Enter starter weight — total weight of the levain you add
4. Set starter hydration — typically 100% for a liquid starter, 50-60% for a stiff levain
5. Select flour type — the calculator shows whether your hydration falls in the recommended range for that flour
6. Read results — total hydration, dough weight, inoculation %, and zone classification

Tips

• Higher hydration (75%+) produces more open crumb but requires strong shaping skills. Start lower and work up.
• Inoculation percentage affects timing more than flavor. 10-15% is typical; lower means longer, more flavorful bulk fermentation.
• Whole grain flours absorb significantly more water. Whole wheat and rye need 75-90% hydration to avoid a dense crumb.
• Autolyse helps — resting flour and water before adding starter lets the flour hydrate fully, making high-hydration doughs easier to handle.
• Adjust for your environment — hot/humid kitchens may need slightly less water; cold/dry environments may need more.
• Weigh everything — volume measurements are unreliable for bread. A kitchen scale accurate to 1g is essential.

FAQ

What hydration should I use for a beginner sourdough?

Start at 65-70% with bread flour. This produces a manageable dough that still gives good oven spring. Once you're comfortable shaping, gradually increase toward 75-80% for more open crumb.

Does starter hydration really matter?

Yes, especially at high inoculation rates. Adding 200g of 50% hydration starter contributes 133g flour and 67g water — very different from 200g of 100% hydration starter which contributes 100g flour and 100g water. The effect on final hydration can be several percentage points.

What is inoculation and how does it affect my bread?

Inoculation is the percentage of pre-fermented flour relative to total flour. Higher inoculation (20%+) means faster fermentation and milder flavor. Lower inoculation (5-10%) means slower fermentation with more complex, acidic flavors — but also higher risk of over-proofing if you're not watching the dough.

Why is my dough too sticky even at 70% hydration?

Several factors beyond hydration cause stickiness: under-developed gluten (knead or fold more), wrong flour type (low-protein flour can't hold as much water), or the dough is over-fermented. Also check that your flour protein content matches what you expect — "bread flour" varies from 11-14% protein depending on brand.

Can I convert a commercial yeast recipe to sourdough?

Yes. Replace the yeast with 15-20% of flour weight in starter. Reduce the recipe's flour and water to account for what's in the starter. Extend bulk fermentation time from 1-2 hours to 4-8 hours (or overnight in the fridge).

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Last reviewed: June 2026