Understanding Sourdough Hydration Basics
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Hydration is one of those terms that sounds technical but describes something very simple: how much water is in your dough relative to the flour. It is expressed as a percentage using baker's math, where the flour is always treated as 100 percent and every other ingredient is measured against it. If a recipe uses 500 grams of flour and 375 grams of water, the hydration is 375 divided by 500, which equals 75 percent. Once you understand this single number, recipes become much easier to read and adjust.
Hydration matters because water controls how a dough behaves at every stage. Higher hydration doughs are wetter, stickier, and more slack, and they tend to produce a more open, airy crumb with large irregular holes, the look many artisan bakers prize. Lower hydration doughs are stiffer, easier to handle, and produce a tighter, more uniform crumb that is well suited to sandwich loaves and shaping-heavy recipes. Neither is better; they simply serve different goals.
For beginners, starting around 65 to 70 percent hydration is wise. Dough in this range is forgiving, holds its shape well, and is far easier to shape and score than a very wet dough. As your handling skills improve you can push toward 75, 80, or even higher, but very high hydration doughs demand confident technique, good gluten development, and often a stronger flour to hold all that water. Jumping to 85 percent too early is a common reason beginners end up with flat, unmanageable puddles.
Remember that your starter contains water too, and it counts toward total hydration. Most starters are kept at 100 percent hydration, meaning equal parts flour and water, so if you add 100 grams of starter you are effectively adding 50 grams of flour and 50 grams of water to your recipe. Accurate bakers include the starter's flour and water in their calculations to know the true hydration of the final dough. Ignoring this can make a recipe wetter than you intended.
Flour type also changes how much water a dough can absorb. Whole grain flours like whole wheat and rye soak up considerably more water than white flour because of their bran and germ, so a 75 percent whole wheat dough will feel much stiffer than a 75 percent white dough. Bread flour, with its higher protein, can hold more water and support higher hydration than all-purpose flour. This is why the same hydration number can feel completely different depending on the flour in the bag.
The practical takeaway is to treat hydration as a dial you adjust to your ingredients, skills, and desired result rather than a fixed rule. Weigh your ingredients with a scale rather than measuring by volume, since flour especially varies enormously by cup. Keep notes on the hydration you used and how the dough felt and baked, and over time you will develop an intuition for exactly how wet you want your dough for the crumb you are chasing.