Sourdough Hydration Guide

Understanding Hydration

In the world of sourdough baking, "hydration" simply refers to the amount of liquid (usually water) in a dough relative to the amount of flour. It is the single most important variable determining the texture, handling characteristics, and final crumb structure of your bread. If you are just starting out, reading our Sourdough Starter Guide will help you get your wild yeast ready before diving into dough mathematics.

Hydration is not expressed in cups or fluid ounces; it is expressed as a percentage. To understand hydration, you must first understand the universal language of professional baking: baker's percentages.

Baker's Percentages Explained

Baker's percentages can seem intimidating at first, but they are incredibly simple once you grasp the core concept: Total flour weight is always 100%.

Every other ingredient in the recipe is calculated as a percentage of that total flour weight. This system allows bakers to scale recipes up or down infinitely without complex math, and it allows them to instantly understand the composition of a dough just by looking at a formula.

An Example Formula

Let's look at a classic, simple sourdough recipe:

• Flour: 500g (This is 100%)
• Water: 375g
• Salt: 10g
• Starter: 100g (Assuming a 100% hydration starter)

To find the hydration percentage, you divide the weight of the water by the weight of the flour, then multiply by 100:

(375g Water ÷ 500g Flour) × 100 = 75% Hydration

To find the salt percentage:

(10g Salt ÷ 500g Flour) × 100 = 2% Salt

Note: For absolute precision, professional bakers calculate "total hydration" by including the water and flour present within the sourdough starter itself. However, for most home baking purposes, calculating the hydration of the main dough ingredients is sufficient.

Low vs. High Hydration Doughs

The amount of water you add drastically changes how the dough behaves on the bench and how it bakes in the oven.

Low to Moderate Hydration (60% - 70%)

This is the ideal starting point for beginners. Doughs in this range are relatively stiff, non-sticky, and easy to knead by hand. They hold their shape very well during proofing and don't spread into a puddle when turned out of the banneton.

The Result: Breads with a tighter, more uniform crumb (fewer large holes). This makes them excellent for sandwiches, toast, and holding butter or jam without it dripping through. If you are baking a standard Basic Sourdough Bread Recipe for the first time, aim for 65-68% hydration to build your confidence.

High Hydration (75% - 85%+)

This is the realm of rustic artisan loaves, ciabatta, and focaccia. High hydration doughs are wet, sticky, and slack. They cannot be traditionally kneaded; instead, they require gentle "stretch and fold" or "coil fold" techniques to build gluten strength without tearing the dough.

The Result: The excess water turns to steam in a hot oven, forcing the dough to expand rapidly. This creates a very open, airy crumb with large, irregular holes (the "wild crumb" many bakers chase). The crust tends to be thinner and crispier. However, these doughs are challenging to shape and require practice to prevent them from flattening out before baking.

How Flour Type Affects Hydration

You cannot simply take a recipe designed for white flour and swap in whole wheat flour without adjusting the hydration. Different flours have drastically different water absorption capacities. This is primarily dictated by protein content and the presence of bran.

• All-Purpose Flour: Absorbs the least amount of water. A 75% hydration AP dough will feel very wet and sloppy.
• Bread Flour: The higher protein content absorbs more water. A 75% hydration bread flour dough will feel tacky but manageable. If you are deciding between the two, read our Sourdough Flour Guide.
• Whole Wheat and Rye Flours: The bran in whole grain flours acts like a sponge, soaking up massive amounts of water. A dough made with 50% whole wheat at 75% hydration will feel quite stiff and dry. When adding whole grains to your recipe, you must increase the water content to achieve the same dough consistency.

Finding Your Perfect Hydration

The "best" hydration depends entirely on the flour you are using and the type of bread you want to eat. The current internet trend heavily favors ultra-high hydration (80%+), but this is not a requirement for excellent sourdough. A perfectly executed 68% hydration loaf is far superior to a poorly shaped, flat 80% hydration loaf.

Start low. Master the process of mixing, bulk fermentation, shaping, and scoring at 65% to 70% hydration. Once you consistently produce well-shaped, well-risen loaves, try increasing the water in your recipe by 2% or 3% at a time. Pay close attention to how the dough feels under your hands. Baking is a tactile craft, and learning to read your dough is far more valuable than blindly following a formula.