You may have noticed that for some sourdough bread recipes there are percentages next to the weights or you may have heard someone say that their sourdough bread was "80% hydration". These refer to baker's percentages or baker's math. Baker's percentages are a way to scale up or down sourdough bread recipes easily, and also to use only one unit of measure (like grams) which enables the baker to be more precise.
In Baker's Percentages, flour is always at 100%, and the rest of the ingredients are a percentage of a flour's weight. So if a baker said that they used 1000g of flour and their hydration was at 80%, this means that they used 800g of water in their recipe.
To determine the percentage of the other ingredients in a recipe the formula is as follows:
(weight of ingredient ÷ weight of flour) x 100 = %
From this, you can adjust the recipe as needed. If you found that the hydration level in this recipe was too high and difficult for you to work with you may want to adjust the recipe's hydration. To do this you would use the following formula.
weight of flour x percentage of ingredient = weight of ingredient
1000 grams x 70% = 700 grams.
Sometimes you will see Baker's Percentages used in recipes beyond sourdough bread but this is less common and not widely used.
Find the rest of our sourdough baking resources here.