What is Sourdough Hydration?

📖 8 min read · Updated 2026

If you have ever wondered why some sourdough breads are dense and chewy while others are light and full of big holes, the answer is almost always hydration. It is the single most important variable in your dough, and understanding it will transform your baking.

Hydration, Simply

Hydration is the ratio of water to flour in your dough, expressed as a percentage. The formula is:

Hydration % = (Water Weight ÷ Flour Weight) × 100

So if you have 500g of flour and 375g of water, your hydration is (375 ÷ 500) × 100 = 75%.

How Hydration Affects Your Bread

Different hydration levels produce dramatically different results:

Low Hydration (50–65%)

Dense, tight crumb. Easy to shape and handle. Perfect for bagels, pretzels, and pizza where you want a chewy bite.

Medium Hydration (70–80%)

The classic sourdough range. Balanced texture, easier to handle than high hydration, but produces a more open crumb than stiff doughs.

High Hydration (80–100%)

Very open crumb with large, irregular holes. Challenging to shape but produces the artisan look associated with the best bakeries. Requires longer fermentation and stronger flour.

How to Choose Your Hydration

If you are a beginner, start at 70–75%. As you gain confidence, push toward 80% for more open crumb. Professional bakers often go to 85–100% for showstopping loaves.

Use our free hydration calculator to find the exact water, salt, and starter amounts for any recipe.

The Bottom Line

Hydration is not a number to memorize — it is a dial you turn to get the bread you want. Lower for structure, higher for openness. The rest is practice.