Understanding Baker's Percentages and Hydration

Every sourdough recipe you've ever seen uses baker's percentages whether you realize it or not. They're the reason one baker in Tokyo and another in San Francisco can follow the same formula and get comparable results, even with different flour brands and different kitchen conditions.

Understanding baker's percentages, and especially hydration, is the single biggest step from "following recipes" to "understanding bread." Once it clicks, you can scale any recipe, adjust on the fly, and troubleshoot problems by looking at the numbers.

What Are Baker's Percentages?

In baker's math, every ingredient is expressed as a percentage of the total flour weight. Flour is always 100%. Everything else is relative to it.

Here's a simple sourdough formula:

The formula is: (ingredient weight / total flour weight) x 100 = baker's percentage

So 375g water / 500g flour = 0.75 x 100 = 75% hydration.

What Is Hydration?

Hydration is the most important baker's percentage. It's the ratio of water to flour, and it fundamentally determines the character of your bread:

• 60-65% hydration: Stiff dough. Dense crumb, easy to handle. Think bagels, pretzels, sandwich bread.
• 65-70% hydration: Moderate. Good structure with some openness. Classic sourdough country loaves.
• 70-75% hydration: The sweet spot for most sourdough. Open crumb, good oven spring, manageable handling.
• 75-80% hydration: Wet dough. Large, irregular holes. Ciabatta territory. Requires confident handling.
• 80%+ hydration: Very wet. Focaccia, high-hydration loaves. Beautiful open crumb but challenging to shape.

The Starter Complication

Here's where it gets slightly tricky. Your sourdough starter contains both flour and water (typically at 100% hydration, meaning equal parts flour and water). This means the starter adds both flour and water to your dough.

For a truly accurate hydration calculation, you need to account for the flour and water in the starter:

• 100g of starter at 100% hydration = 50g flour + 50g water
• Total flour in the recipe = 500g + 50g (from starter) = 550g
• Total water = 375g + 50g (from starter) = 425g
• True hydration = 425 / 550 = 77.3%

This is why a recipe that says "75% hydration" is actually closer to 77% when you include the starter. For most home baking, the difference is minor, but understanding it matters when you're fine-tuning.

How to Adjust Hydration

If your bread isn't turning out the way you want, hydration is often the lever to pull:

Problem: Dense, tight crumb

Try increasing hydration by 3-5%. More water creates more steam during baking, which opens up the crumb structure.

Problem: Dough too sticky to shape

Either reduce hydration by 2-3% or improve your handling technique. Wet hands, bench scrapers, and quick confident movements make wet doughs manageable.

Problem: Flat loaf, no oven spring

This is usually a fermentation issue, not hydration. But if hydration is above 78%, the dough may be too slack to hold its shape. Consider dropping to 73-75%.

Problem: Gummy interior

Over-hydration relative to your flour's absorption capacity. Whole wheat and rye absorb more water. White bread flour absorbs less. Match hydration to your flour.

Flour Absorption and Why It Varies

Different flours absorb different amounts of water. This is why the same hydration percentage can produce very different doughs depending on what flour you use:

• White bread flour: Moderate absorption. 75% hydration is a good starting point.
• Whole wheat: High absorption. You may need 80-85% hydration for a similar dough consistency.
• Rye: Very high absorption. Rye doughs are sticky regardless. 80%+ is typical.
• Type 00: Lower absorption. 65-70% hydration for a workable dough.

Putting It Into Practice

The best way to understand hydration is to bake the same formula at different hydration levels. Try your standard recipe at 68%, 73%, and 78%. Keep everything else the same (flour, fermentation time, oven temperature). The difference in the final loaf will teach you more about hydration than any article can.

And once your dough is mixed, the next critical step is bulk fermentation. Our guide to bulk fermentation walks you through timing, temperature, and how to judge when your dough is ready.