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Sourdough Hydration Calculator.

Calculate total flour, water, hydration, and starter percentage from explicit sourdough masses.

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How to Use

Starter hydration splits starter mass into flour and water; total hydration is total water ÷ total flour × 100.

Enter values from your recipe, measurement, or planning convention. This page does not provide food-safety or nutrition advice.

Use Cases

Adjusting a sourdough recipe

When you want to scale a recipe up or down, this calculator helps you see the resulting hydration and starter percentage so you can maintain the same dough characteristics.

Example: If you increase flour and water proportionally, hydration stays the same, but starter percentage may change if starter mass isn't scaled.

Creating a custom sourdough formula

Bakers can experiment with different amounts of flour, water, and starter to achieve a desired hydration level, such as a 75% hydration dough for a rustic loaf.

Example: Try 500g flour, 350g water, and 100g starter to see the resulting percentages.

Frequently Asked Questions

What does the Sourdough Hydration Calculator do?
It takes the explicit masses of flour, water, and starter you plan to use and calculates the total flour, total water, overall hydration percentage, and the percentage of starter relative to total flour. This helps you understand your dough's consistency and adjust recipes.
How is hydration percentage calculated?
Hydration is the ratio of total water (including water from the starter) to total flour (including flour from the starter), expressed as a percentage. For example, if total water is 700g and total flour is 1000g, hydration is 70%.
Why is starter percentage important?
Starter percentage (starter mass divided by total flour mass) indicates how much prefermented flour is in your dough. A higher percentage can speed up fermentation and add more sour flavor, while a lower percentage slows it down.

Tips & Common Mistakes

Tips

  • Remember that the starter contributes both flour and water to the total. If your starter is 100% hydration (equal parts flour and water), half of its mass is flour and half is water.
  • Use a kitchen scale for accurate measurements. Hydration percentages are only as precise as your inputs.
  • For a stiffer dough, aim for lower hydration (60-65%). For a wetter, more open crumb, aim for higher hydration (75-80%).
  • Check your starter's hydration level. If it's not 100%, adjust the calculation accordingly, but this calculator assumes you input the flour and water masses separately.

Common Mistakes to Avoid

  • Forgetting that the starter contains both flour and water, so you must include those in the total flour and water calculations.
  • Using volume measurements (cups) instead of weight (grams), which leads to inaccurate hydration percentages.
  • Assuming the starter percentage is based on total dough weight instead of total flour weight.

Last updated: August 13, 2026