In artisanal bread baking, hydration controls crumb openness, dough extensibility, and crust blistering. Yet many home bakers calculate hydration incorrectly by ignoring the liquid in their starter.
The Baker's Percentage Rule
In baker's percentages, total flour is always set at 100%. Every other ingredient (water, salt, levain) is expressed as a weight ratio relative to that flour baseline:
Apparent Hydration = (Added Water Weight ÷ Recipe Flour Weight) × 100
The Common Mistake: Ignoring Sourdough Starter
A standard active sourdough starter is maintained at 100% hydration (equal parts flour and water by weight). If a recipe includes 100g of starter, it contains 50g of flour and 50g of water.
True Total Hydration = [(Added Water + Starter Water) ÷ (Recipe Flour + Starter Flour)] × 100
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