Sourdough Hydration Explained — What Baker's Percentages Mean and How to Adjust

Hydration is one of the most discussed variables in sourdough baking — and one of the most misunderstood. It affects how the dough handles, how open the crumb is, how the crust develops, and how difficult the whole process is. This guide explains what hydration actually means, how baker's percentages work, and how to find the right hydration for your flour and baking style.

What Is Hydration?

Hydration refers to the ratio of water to flour in your dough, expressed as a percentage. A dough made with 750g of water and 1000g of flour is 75% hydration. This number tells you how wet or stiff the dough is — and it's the starting point for understanding how a recipe will handle.

What Are Baker's Percentages?

Baker's percentages express every ingredient as a proportion of the total flour weight (not the total dough weight). Flour is always 100%. Everything else is calculated against that:

• 1000g flour = 100%
• 750g water = 75% (hydration)
• 200g levain = 20%
• 20g salt = 2%

This system makes it easy to scale recipes up or down and to compare recipes regardless of batch size. If a recipe says 75% hydration and yours says 80%, you know exactly what's different without having to reverse-engineer the gram quantities.

How Hydration Affects Your Bread

Hydration changes almost everything about how the dough behaves and how the bread turns out:

Why High Hydration Isn't Always Better

Many bakers assume higher hydration equals better bread, but that's not accurate. The highly open, irregular crumb you see in bakery loaves is the result of many factors — starter health, flour quality, fermentation management, and shaping skill — not just high hydration. A 70% hydration loaf made by an experienced baker with great flour and technique will outperform a 85% hydration loaf made by a beginner. Start lower and increase gradually as your handling skills develop.

How Flour Type Affects Absorption

Different flours absorb water differently, which means the same hydration percentage produces different dough textures depending on the flour:

• High-protein baker's flour (12%+ protein): Absorbs water well and handles high hydration more easily. This is the best base for most sourdough recipes.
• Whole wheat or wholemeal flour: Absorbs significantly more water due to the bran. Adding 10–20% whole wheat to a recipe typically requires adding 3–5% more water to maintain the same dough consistency.
• Rye flour: Absorbs a lot of water and doesn't develop gluten the same way. A 100% rye dough at 75% hydration will be very slack. Treat rye doughs as a different category.
• Plain or all-purpose flour: Lower protein, absorbs less water. Not ideal for sourdough, but if you use it, reduce hydration by 5%.

Our Understanding Sourdough Flours guide covers flour types in detail.

How to Adjust Hydration

When changing hydration, change it gradually — 2–3% at a time. Going from 70% to 80% in one step makes it impossible to know what changed and why. Keep everything else constant so you're learning what hydration alone does.

To increase hydration: add the extra water in a small separate step (called autolyse or bassinage) after the initial mix, working it in gradually with your hands.

What Hydration Should You Start With?

For most Australian home bakers using standard baker's flour from a supermarket:

• Start at 70–72% until you can shape dough cleanly and consistently
• Move to 75% once you're comfortable and want a more open crumb
• Try 78–80% once you've mastered stretch and fold and shaping

Our Classic Sourdough recipe is written at 75% hydration — a good target for home bakers with a few bakes under their belt. Browse our sourdough starter kits to get started with a reliable culture.