When sourdough bread turns out dense, the first piece of advice is often to add more water. It sounds simple: wetter dough should stretch more easily, the bubbles should grow larger, and the crumb should become lighter.

In practice, hydration does not work quite so directly. More water can help create an airy crumb, but only while the flour and gluten structure are strong enough to hold it. If the dough cannot manage the additional water, the loaf may spread, lose its shape, and develop a damp or gummy crumb instead of beautiful open holes.

The best hydration is therefore not the highest percentage you can mix. It is the amount of water your flour can absorb and your dough can retain throughout fermentation, shaping, and baking.

Hydration is the amount of water in a dough expressed as a percentage of the total flour weight.

For example, a dough made with 500 grams of flour and 350 grams of water has 70% hydration:

However, the flour and water contained in your sourdough starter must also be included.

Suppose your recipe contains:

The starter contains 50 grams of flour and 50 grams of water. This means the real totals are 550 grams of flour and 400 grams of water:

Although the recipe may appear to have 70% hydration at first glance, its true hydration is almost 73%.

This difference becomes especially important when a recipe contains a large amount of starter.

There is no strict rule that connects one hydration percentage with one exact crumb structure. Flour strength, the amount of whole-grain flour, fermentation, mixing, and shaping all affect the result. Still, the following ranges provide a useful starting point.

At this level, the dough is relatively firm and easy to handle. It holds its shape well and is less likely to stick to the hands or work surface.

The crumb is usually even and moderately dense. This hydration can work well for beginner-friendly loaves, shaped breads, or flour that absorbs little water.

A properly fermented 65% dough can still be light and pleasant. It simply may not produce the dramatic open crumb associated with very wet sourdough.

For many white bread flours, this is the most practical range. The dough is soft enough to expand well but usually remains strong enough to shape without excessive difficulty.

At approximately 70% hydration, you can achieve a light, irregular crumb without turning the dough into an unmanageable mass.

If you are trying to improve the airiness of your bread, this is usually a better starting point than immediately jumping to 80%.

The dough becomes softer, stickier, and more extensible. With strong flour and good gluten development, this range can produce a more open crumb and larger irregular holes.

However, fermentation becomes more difficult to judge. Wet dough often looks very bubbly, even before it has developed enough strength. It also ferments quickly and may weaken sooner in a warm kitchen.

Gentle folds and careful shaping are especially important at this hydration.

Very high-hydration dough can create a beautifully open crumb, but the percentage alone guarantees nothing.

The flour must absorb enough water, the gluten must be developed well, and fermentation must finish at the correct moment. Otherwise, the dough may spread after shaping and bake into a flat loaf with a shiny, sticky crumb.

Hydration above 80% is not automatically better. It is simply suitable for certain types of flour, recipes, and techniques.

Two flours can behave completely differently at the same hydration.

Strong bread flour with a higher protein content usually absorbs more water and forms a stronger gluten network. It can often handle hydration of 72–78% while still holding its shape.

Weaker all-purpose flour may feel very loose at the same percentage. In that case, reducing the water is not a failure. It is an adjustment to the flour you are actually using.

Whole-wheat flour absorbs a great deal of water, but it does not always create a more open crumb. Bran particles can cut through and interfere with the gluten network. The dough may need more water while producing smaller, more even holes.

Rye flour also absorbs plenty of water, but it does not build the same elastic gluten structure as wheat flour. Adding rye can make the bread moist and flavorful, but it usually creates a tighter crumb.

This is why hydration percentages from different recipes cannot always be compared directly.

When hydration is too high for the flour, the dough never develops enough strength. It remains sticky, flows outward, and cannot hold the gas created during fermentation.

A very wet dough may also tempt you to extend bulk fermentation while waiting for it to become stronger. But additional time does not always solve the problem. Once the gluten begins to weaken, the dough becomes even looser.

Excessive hydration can cause:

These problems are sometimes blamed on shaping or the starter when the flour simply received more water than it could support.

Begin with a hydration level that already gives you a loaf capable of holding its shape. For many bakers, this will be around 68–72%.

Instead of adding a large amount of water at once, increase it by approximately 10–15 grams in your next loaf.

For a dough containing 500 grams of flour, an extra 10 grams of water changes the hydration by only about two percentage points. This small adjustment is enough to notice a difference without completely changing the way the dough behaves.

You can also hold back part of the water during mixing. Combine the flour with most of the water and let it rest for 20–40 minutes. Then add the starter and salt.

Introduce the remaining water gradually only if the dough can absorb it. This method, often called bassinage, gives you more control than adding all the water at the beginning.

If the dough becomes smoother and stronger as the water is incorporated, you can continue. If it starts losing structure and turning into a flowing mass, stop. You do not have to use every gram listed in the recipe.

Hydration creates the conditions for an open crumb, but it cannot compensate for weak fermentation or poor gluten development.

The starter must be active enough to produce gas. The dough must develop a network capable of holding that gas. Bulk fermentation must continue long enough for the crumb to become light, but not so long that the gluten weakens.

Shaping also matters. Pressing all the gas from a well-fermented dough will produce a more uniform crumb. At the same time, shaping too loosely can leave the loaf without enough surface tension to rise upward.

Finally, strong initial heat and steam allow the dough to expand before the crust sets.

A well-fermented 70% hydration dough can be more open and airy than a poorly handled dough at 80%.

Do not choose hydration according to photographs of someone else’s loaf. Begin with your flour, your kitchen temperature, and your current experience with the dough.

If the loaf holds its shape but the crumb remains tight, increase the water slightly and examine the fermentation as well. If the dough spreads, becomes extremely sticky, or produces a damp crumb, reduce the hydration until its strength returns.

The ideal amount of water is the point at which the dough feels soft and extensible but still elastic. It should spread slightly during rest, then regain structure after folding. After shaping, it should remain stable instead of flowing across the work surface.

An airy crumb does not come from chasing the highest possible number. It comes from finding a balance between water, flour strength, fermentation, and handling.

Once you find that balance, even a moderate-hydration dough can produce a beautifully light loaf with an irregular crumb, good volume, and a crisp crust.