Sourdough Hydration Calculator

How It Works

Hydration in bread baking is expressed as the ratio of water to flour by weight. A 75% hydration dough contains 75 g of water for every 100 g of flour. This calculator accounts for the flour and water already present in your levain (sourdough starter).

• Levain hydration — a 100% hydration levain is equal parts flour and water by weight. A stiffer levain (e.g., 60%) has more flour relative to water.
• Levain percentage — the amount of levain as a percentage of total flour. 20% is standard for a ~4–6 hour bulk fermentation at room temperature.
• Salt — typically 1.8–2.2% of total flour weight. Salt strengthens gluten and controls fermentation rate.

The calculator splits the levain into its flour and water components, then computes the remaining flour and water you need to add to hit your target hydration precisely.