If you've spent any time in the sourdough world, you've probably heard bakers toss around the term "hydration" like it's common knowledge. "This is a 75% hydration dough." "Try lowering your hydration to 70%." But what does that actually mean, and why does it matter so much?
Don't worry—hydration is one of those concepts that sounds more complicated than it is. Once you understand it, you'll have a powerful tool for predicting how your dough will behave and troubleshooting problems before they happen. Let's break it down.
What Is Hydration?
In the simplest terms, hydration is the ratio of water to flour in your dough, expressed as a percentage. That's it. Nothing mysterious, no complicated math required.
Here's the formula: Hydration % = (Water weight ÷ Flour weight) × 100
So if you're using 500 grams of flour and 375 grams of water, your hydration is 75% (375 ÷ 500 × 100 = 75). The dough is three-quarters water by weight compared to the flour.
This percentage tells you a lot about what to expect from your dough—how it will feel, how it will behave during shaping, and even what the final crumb will look like.
Why Does Hydration Matter?
Hydration affects nearly every aspect of your sourdough bread. Understanding it helps you choose the right recipe for your skill level and desired outcome.
Dough consistency: Higher hydration means wetter, stickier dough that's harder to handle but can produce those gorgeous open crumbs with big, irregular holes. Lower hydration doughs are stiffer, easier to shape, and create a tighter, more even crumb.
Fermentation speed: Wetter doughs ferment faster because the water helps enzymes and microorganisms move around more easily. Drier doughs take longer to ferment.
Oven spring: Higher hydration doughs generally have more dramatic oven spring—that beautiful upward leap your bread makes when it first hits the heat.
Crust and crumb: Hydration affects texture too. Higher hydration typically yields a chewier crust and more open, custardy crumb. Lower hydration creates a softer crust and closer, more sandwich-friendly crumb.
Common Hydration Levels and What They Mean
Let's look at some common hydration percentages and what you can expect from each.
60-65% Hydration (Low)
This is stiff dough territory. Think bagels, pretzels, or traditional pan loaves. These doughs are easy to handle, hold their shape well, and produce bread with a tight, even crumb. If you're brand new to bread baking, this is a comfortable place to start.
70-75% Hydration (Medium)
This is the sweet spot for most home bakers and many classic sourdough recipes. At 70-75%, you get dough that's manageable but still sticky enough to develop good gluten and create a nice open crumb. It requires some technique to handle, but it's not intimidating once you get the hang of it.
80-85% Hydration (High)
Now we're talking wet, extensible dough that spreads and sticks to everything. These doughs demand good technique—strong gluten development, confident handling, and often a banneton for support. The reward? Dramatic open crumb, big holes, and that artisan bakery look. Ciabatta lives here.
90%+ Hydration (Very High)
This is expert territory. Doughs this wet are almost batter-like and require advanced handling skills. Some focaccias and ultra-high-hydration sourdoughs fall into this category. Beautiful results, but not where you want to start your sourdough journey.
How to Calculate Your Dough's Hydration
Let's walk through a real example. Say your recipe calls for:
- 500g bread flour
- 50g whole wheat flour
- 400g water
- 100g active sourdough starter (at 100% hydration)
- 11g salt
First, we need to account for the flour and water in your starter. If your starter is at 100% hydration (equal parts flour and water by weight), that 100g breaks down to 50g flour and 50g water.
Total flour: 500g + 50g + 50g (from starter) = 600g
Total water: 400g + 50g (from starter) = 450g
Hydration: (450 ÷ 600) × 100 = 75%
See? Not so scary. The salt doesn't factor into hydration calculations, by the way—we only count flour and water.
How Flour Type Affects Hydration
Here's something that trips up a lot of bakers: different flours absorb water differently. A 75% hydration dough made with bread flour will feel completely different from a 75% dough made with whole wheat flour.
Whole grain flours (whole wheat, rye, spelt) absorb significantly more water than white flours because the bran acts like a sponge. If you're substituting whole wheat for white flour in a recipe, you'll likely need to increase hydration by 5-10% to get a similar dough consistency.
High-protein bread flour absorbs more water than all-purpose flour, which absorbs more than low-protein cake flour.
This is why you can't judge a recipe by hydration percentage alone. A 75% dough made with 100% bread flour will feel stiffer than a 75% dough with 30% whole wheat flour mixed in.
Tips for Working with Different Hydrations
Starting out? Stick with 70-72% hydration while you're learning. It's forgiving enough to handle but still produces beautiful bread. You can always experiment with higher hydrations once you've built your confidence and technique.
Adjust for your environment: In humid climates, you might find your dough feels wetter than expected at a given hydration percentage. In dry climates, it might feel stiffer. Don't be afraid to adjust by 2-3% to get the consistency you want.
Use the autolyse technique: Mixing just flour and water first (before adding starter and salt) and letting it rest for 30 minutes to an hour helps the flour fully hydrate. This makes higher hydration doughs more manageable.
Build your gluten well: Higher hydration doughs rely on good gluten structure to hold their shape. Use techniques like stretch and folds, coil folds, or slap and folds to develop strength without overworking the dough.
Keep your hands wet or oiled: When handling sticky, high-hydration doughs, slightly damp or oiled hands prevent sticking and make shaping much easier.
Don't Be Intimidated by High Hydration
I see a lot of new bakers intimidated by recipes with 80%+ hydration. Here's the truth: high hydration isn't necessarily better. It's just different.
Yes, those Instagram-worthy loaves with massive holes often come from high-hydration doughs. But plenty of incredible breads live in the 65-75% range. The best hydration is the one that matches your skill level, your flour, and the kind of bread you want to make.
Some of the most delicious sourdough I've ever eaten had a relatively tight crumb from a lower hydration dough. It was perfectly balanced, deeply flavorful, and ideal for slicing and using throughout the week. That's just as valid as a high-hydration showstopper.
Finding Your Hydration Sweet Spot
My advice? Pick a hydration level and stick with it for several bakes. Make the same recipe with the same hydration three or four times. Get to know how that dough feels, how it ferments, how it handles.
Once you're comfortable, try adjusting by 5% in either direction. Notice how the dough behaves differently. Does it feel too wet? Too stiff? Does the crumb open up or tighten? This hands-on experience is worth more than any article (even this one!).
Keep notes. I'm serious. Jot down your hydration percentage, how the dough felt, how long bulk fermentation took, and how the final loaf turned out. Over time, you'll develop an intuition for hydration that guides your baking.
The Bottom Line
Hydration is simply the ratio of water to flour in your dough. It's not something to fear or obsess over—it's a tool that helps you understand what to expect from your dough and how to adjust when things aren't quite right.
Start where you're comfortable, probably around 70-75% for your first loaves. As your skills grow, experiment with different hydration levels to discover what you enjoy baking and eating most.
Remember, there's no "perfect" hydration. There's only the right hydration for you, your flour, your environment, and the bread you want to create. Happy baking!