Sourdough Hydration Calculator

Use this Sourdough Hydration Calculator to include the flour and water inside your starter when calculating dough hydration.

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How to Use the Sourdough Hydration Calculator

Enter main flour and water in grams, starter weight and its hydration percentage. Add any extra flour or water separately, without counting them again in the main ingredients. The default starter hydration is 100%, meaning equal flour and water by weight. Optionally enter a target overall hydration to calculate a recipe water adjustment.

Formula and Explanation

Starter flour = starter weight ÷ (1 + starter hydration / 100)
Starter water = starter weight − starter flour
Total flour = main flour + extra flour + starter flour
Total water = main water + extra water + starter water
Overall hydration = total water ÷ total flour × 100
Target water adjustment = target / 100 × total flour − total water

Baker’s hydration is water as a percentage of flour, not of total dough weight. A 100%-hydration starter contains half flour and half water by weight. A stiffer or wetter starter has a different split. The target calculation holds total flour fixed: a positive adjustment means more recipe water; a negative adjustment means the target recipe requires less water than already entered.

This counts water and flour entered directly plus their modeled starter portions. It does not infer moisture from eggs, milk, fruit, cooked flour or other ingredients. Targeting a number does not guarantee dough handling or fermentation results. If the target needs less water, adjust the recipe before mixing; this is not a method for extracting water from mixed dough.

Worked Example

With 500 g main flour, 350 g main water and 200 g of 100%-hydration starter, the starter adds 100 g flour and 100 g water. Totals are 600 g flour and 450 g water, so hydration is 75%. A target of 80% needs 480 g total water, or 30 g more. A target of 70% needs 420 g water: 30 g less than entered, not a negative addition.

Frequently Asked Questions

Is 100% starter hydration the same as 100% dough hydration?

No. Starter hydration describes that ingredient’s water-to-flour ratio. Overall dough hydration includes all entered flour and water, including the starter contributions.

Does starter weight count entirely as flour?

No. It is split using the starter hydration. For example, 200 g at 100% hydration contributes 100 g flour and 100 g water.

What if the target is below the current hydration?

The result shows how much less water the target recipe needs. It does not suggest adding a negative amount. Adjust the planned recipe before mixing.

Can I calculate hydration without starter?

Yes. Set starter weight to zero and enter the flour and water directly. Total flour must still be greater than zero to define a hydration percentage.