The Science of Hydration in Sourdough Bread

Many of us are intimidated by the big words we find in sourdough recipes and in the “shop talk” we hear from bakers.

I am committed to guiding you (see what I did there?) so you can better understand what is happening.

Simply put: Hydration refers to the ratio of flour and water (or other liquids, like beer, milk, juice…).

Example: The starter we use in most recipes has equal amounts of water and flour. The result is a 100% hydration.

As a reference, I built this calculator

Sourdough Bread Hydration Calculator

You simply add up all the flour you are adding to the bread and slide the slider for the water. The calculator will give you the hydration level of your dough.

The hydration of your dough influences the outcome. Some breads typically have a higher hydration, like baguette for example. Others, like sandwich loaves, have a lower hydration.

There is no right or wrong in this, but there are advantages and reasons for the different hydration levels:

Lower hydration <80%

The dough is easier to handle, especially for beginner bakers

A more even and closed crumb allows for easier spreading of toppings.

This bread can feel heavier

Lower oven-spring means that the loaves don’t rise as high

Higher hydration >80%

High-hydration dough needs more experience to handle

Bigger alveoli (holes) produce a more “airy” bread

Some say the bread feels moister

More and larger alveoli mean that the loaves rise higher in the oven

Bakers Math

Sometimes you will come across terms like “bakers math” or “Bakers percentage”.

While this sounds very mysterious it is a way for us to communicate a bread recipe in simple percentages. If you read bread recipes and you use regular math, you will notice, that the result is more than 100% 😮 .
This is because bakers list percentages in relation to the amount of flour.

If you are even more confused now, let me explain why we do this:

  1. You can scale up any bread recipe by using the listed percentages.
  2. You can predict the bread’s behaviour, crumb structure, how difficult it will be to handle, rise times….
  3. Quickly communicate the basics of your recipe.

The percentages of all ingredients are expressed in relation to the weight of the flour used. This is another reason bakers use a scale rather than cup measurements.

Let’s use an example:

My basic bread recipe uses 500 grams of flour per loaf at 72% hydration. We want to make three loaves:

1 loaf

Flour 500 g (100 g Spelt, 150 g whole wheat, 250 g white)

Water 360 g

60 g starter (100% hydration)

3 loaves

Flour 1500 g

Water 1,080 g

180 g starter

You can imagine that this can get complicated if you bake more than just 3x the basic recipe.

You can also use my calculator:

calculator for 3 laves baker's math

Learn more

If you want to dive deeper into this topic, I recommend this article by Bake & Basil
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