Understanding Bakers Percentages

What is Hydration in Sourdough and How to Calculate It

Hydration percentage refers to the amount of water in a recipe relative to the weight of the flour. This is also known as Baker’s Percentage. Unlike a traditional percentage, the total ingredients won’t add up to 100%. Instead, each ingredient is expressed as a percentage of the flour weight.

In sourdough baking, there are some common rules of thumb for ingredients:

• Starter: Usually 10–20% of the total flour weight.

• Salt: Typically 2% of the flour weight.

To calculate hydration percentage, use this formula:

(Total weight of water ÷ Total weight of flour) × 100 = Hydration %

When using a sourdough starter, remember to include the water and flour from the starter. For example, a 100% hydration starter is equal parts water and flour.

Example Calculation

Let’s break it down with an example:

• 500g bread flour

• 350g water

• 50g starter (100% hydration)

• 10g salt

Step 1: Calculate the total flour and water

• Flour: 500g from the recipe + 25g from the starter = 525g total flour

• Water: 350g from the recipe + 25g from the starter = 375g total water

Step 2: Calculate the hydration percentage

• 375 ÷ 525 = 0.714 × 100 = 71% hydration

Calculating Baker’s Percentages for Other Ingredients

For other ingredients, divide the ingredient weight by the total flour weight and multiply by 100. Using the same example:

• Starter:
  • 50 ÷ 500 = 0.1 × 100 = 10%

• Salt:
  • 10 ÷ 500 = 0.02 × 100 = 2%

Ignoring Starter Contributions

If you ignore the starter’s contribution to water and flour, the hydration would be slightly lower:

• 350 ÷ 500 = 0.7 × 100 = 70%

This example shows that omitting the starter’s water and flour in calculations can result in a small but noticeable difference in hydration percentage. Always include your starter amounts for accurate results.