Sourdough Hydration Explained: Baker's Percentages, 65–85%

Hydration is the single number that tells you the most about a sourdough dough before you touch it: how sticky it will be, how it will shape, and what kind of crumb to expect. It’s also the source of a lot of confusion, mostly because of one detail: does the water in your starter count?

This guide explains baker’s percentages, what really changes between 65% and 85% hydration, and how to do the math, with real numbers.

What is sourdough hydration?

Hydration is the weight of water divided by the weight of flour, expressed as a percentage.

Hydration % = water ÷ flour × 100

A dough with 1,000 g flour and 700 g water is 70% hydration. That’s all. Because it’s a ratio, the same hydration describes a small loaf and a bakery batch.

Two things to keep in mind:

• It’s always by weight, never by volume.
• It’s always relative to flour, not to the total dough weight.

Baker’s percentages in 60 seconds

Hydration is one example of a wider system called baker’s percentages. In a formula, total flour is always 100%, and every other ingredient is written as a percentage of that flour weight.

A typical country loaf might look like this:

Ingredient	Baker’s %	For 500 g flour
Flour	100%	500 g
Water	72%	360 g
Starter (levain)	20%	100 g
Salt	2%	10 g

The percentages add up to more than 100%, and that’s expected. The advantage is that you can scale any recipe up or down just by choosing a new flour weight, and you can compare recipes at a glance. The baker’s percentage recipe scaler does this for any formula.

Hydration ranges: what changes from 65% to 85%

These describe doughs made mostly with white bread flour. Other flours shift the feel (see the next section).

Hydration	How the dough feels	Typical crumb	Common uses
60–65%	Firm, smooth, easy to shape	Tight, even	Bagels (often lower), sandwich loaves, pretzels
66–70%	Soft, slightly tacky, very manageable	Moderate, fairly even	Beginner loaves, pan loaves, many pizza doughs
71–75%	Tacky and extensible, benefits from folds	Open, irregular	Classic country loaves
76–80%	Sticky and slack, needs strength-building	Open, glossy, larger holes	Open-crumb loaves, many ciabatta
81–85%+	Very wet, hard to shape free-form	Big irregular holes	Focaccia, ciabatta, show-off open crumb

As hydration rises:

• Handling gets harder. You’ll rely more on wet hands, a bench scraper and folds.
• Gluten development matters more. Coil folds or stretch and folds during bulk give wetter doughs the structure to hold their shape.
• Fermentation tends to run a little faster, since wetter dough is easier for microbes to work through. The bulk fermentation chart gives typical bulk and proof times by temperature for a dough around 75% hydration; check the dough a little earlier if yours is wetter.
• The crumb opens up, but only if fermentation and shaping are right. High hydration alone doesn’t guarantee big holes; underproofed wet dough can still bake dense.
• Crust and bake change. Wetter doughs often need the full bake time to avoid a gummy crumb.

Flour changes everything

The same hydration can feel completely different with a different flour:

• Whole wheat absorbs more water. A dough with a large share of whole wheat often needs 5–10 percentage points more water to feel like its white-flour version.
• Rye absorbs a lot of water but forms little gluten, so rye doughs are sticky and paste-like at any hydration.
• Low-protein all-purpose flour absorbs less than bread flour, so a 75% dough will feel wetter and weaker.
• Freshly milled and high-extraction flours often drink more water and may need a longer rest to absorb it.

That’s why a recipe’s hydration is a starting point. The same 75% can be easy with one bag of flour and soupy with another.

The starter counts too: nominal vs total hydration

Your starter is made of flour and water, so it adds both to the dough.

A 100% hydration starter is half flour, half water by weight. So 100 g of it contributes 50 g flour + 50 g water.

This gives two ways to state hydration:

• Nominal hydration: water ÷ main flour, ignoring the starter. Many recipes use this.
• Total (true) hydration: all water ÷ all flour, including what’s in the starter.

For typical loaves with 10–25% starter, the two numbers differ by only a point or three. With a lot of starter, or a stiff starter, the difference grows. What matters is knowing which one a recipe uses.

Worked example: a country loaf

Here’s Boulie’s Classic Country Loaf:

• 400 g bread flour
• 50 g whole wheat flour
• 340 g water
• 90 g active starter (100% hydration)
• 9 g salt

Nominal hydration (ignoring the starter):

• Flour: 400 + 50 = 450 g
• Water: 340 g
• 340 ÷ 450 = 75.6%

Total hydration (including the starter):

• The starter adds 45 g flour and 45 g water
• Flour: 450 + 45 = 495 g
• Water: 340 + 45 = 385 g
• 385 ÷ 495 = 77.8%

Other baker’s percentages, based on the 450 g main flour: starter 20%, salt 2%. With 11% whole wheat, you can see why the dough handles well even at a total hydration close to 78%: bread flour and a bit of whole grain soak up a lot of water.

Worked example: scaling to a target dough weight

Say you want 1,000 g of dough at 75% hydration, 20% starter and 2% salt (all relative to main flour).

1. Add up the percentages: 100 + 75 + 20 + 2 = 197%
2. Find the flour: 1,000 ÷ 1.97 ≈ 508 g flour
3. Everything else:
   • Water: 508 × 0.75 ≈ 381 g
   • Starter: 508 × 0.20 ≈ 102 g
   • Salt: 508 × 0.02 ≈ 10 g

That’s 75% nominal. The total hydration, counting the starter’s 51 g flour and 51 g water, is (381 + 51) ÷ (508 + 51) = 432 ÷ 559 ≈ 77.3%.

If you want 75% total hydration, reduce the water by about 12 g, to 369 g: (369 + 51) ÷ 559 ≈ 75.1%.

The sourdough hydration calculator handles both versions and the starter adjustment automatically.

Starter hydration: 100% vs stiff

Not every starter is 100% hydration:

• Liquid starters (100–125%) are easy to stir and feed, and their contribution is simple to calculate.
• Stiff starters (50–60%), like Italian lievito madre, ferment more slowly and are often described as giving a milder, less sour flavor.

With a stiff starter, the flour and water it contributes are no longer equal. For a 50% hydration starter, 100 g contains about 67 g flour and 33 g water. If you swap starter types in a recipe, recalculate, or the dough will be noticeably wetter or drier than intended.

Choosing a hydration: practical tips

• Start at 68–72% with bread flour, then work up 2–3% at a time.
• Hold back 5–10% of the water when trying a new flour. Add it during the first set of folds if the dough can take it. Bakers call this bassinage.
• Adjust for flour, not just the recipe. More whole grain means more water.
• Watch the dough, not only the number. Humidity, flour age and even the brand change how much water it needs.
• Only increase hydration once shaping is reliable. A well-fermented, well-shaped 70% loaf beats a badly shaped 82% one.

A strong, active starter makes every hydration easier to manage. If you’re not sure yours is at its best, see how to tell when your sourdough starter is ready.

How Boulie helps

Boulie has a built-in hydration calculator that uses baker’s percentages, so you can check or adjust a formula without doing the math on paper. Its 100+ step-by-step recipes, from country loaves and focaccia to bagels and pizza, come with guided bake mode and alarms, and the photo bake journal lets you note what hydration you used alongside how the crumb turned out, which is the fastest way to find the hydration that works with your flour.

Key takeaways

• Hydration = water ÷ flour × 100, always by weight.
• In baker’s percentages, flour is 100% and everything else is relative to it.
• 65–70% is forgiving; 75–80% opens the crumb; 80%+ is for focaccia, ciabatta or experienced hands.
• Your starter adds flour and water. Know whether a recipe quotes nominal or total hydration.
• Flour type can matter as much as the number itself.