August 3, 2026
The Complete Sourdough Hydration Guide
Hydration is the single number that decides what kind of bread your dough becomes. It determines the crumb, the crust, the shape you can build, the folds you need, and how long fermentation takes. This guide explains exactly what it means, how to calculate it correctly (including the starter, which most guides get wrong), and how to choose the right level for your next loaf.
What hydration actually means
Hydration is the weight of water divided by the weight of flour, expressed as a percentage. A 70% dough contains 70 g of water for every 100 g of flour.
Why bakers talk in percentages instead of grams: percentages describe the character of a dough, not its size. “75% hydration, 2% salt” is the same bread at 500 g of flour or 5 kg of flour. When you scale a recipe up or down, the percentages stay fixed; only the grams change. That is the entire idea behind baker’s math, and it is why every serious sourdough formula you will meet is written this way.
The formula
True hydration % = (total water ÷ total flour) × 100The word “total” is the trap. Most home recipes list only the water you pour in and the flour you scoop out. But if you use a starter, you are already adding both flour and water without measuring them:
- A 100%-hydrated starter is 50% flour and 50% water by weight.
- A 200%-hydrated (liquid) starter is one-third flour and two-thirds water.
Worked example: the starter that hides 2.7%
Take the classic formula: 500 g flour, 350 g water, 100 g of 100%-hydrated starter, 10 g salt.
- Starter flour = 100 g × 50% = 50 g
- Starter water = 100 g × 50% = 50 g
- Total flour = 500 + 50 = 550 g
- Total water = 350 + 50 = 400 g
- True hydration = 400 ÷ 550 × 100 = 72.7%
The recipe says 70% (350 ÷ 500), but the dough is actually 72.7% hydrated. That is not a rounding error; it is a 2.7-point difference in gluten hydration, fermentation speed and crumb openness. This is exactly the math our sourdough hydration calculator does for you.
What each hydration level does
| Hydration | Dough feel | Crumb | Best for |
|---|---|---|---|
| 55–60% | Stiff, dry-ish, easy to handle | Tight, dense | Bagels, pretzels, stiff sandwich loaves |
| 65–70% | Firm, slightly tacky, shapeable | Even, close | Beginner loaves, whole wheat, everyday bread |
| 75% | Slack, sticky, needs a scraper | Open, airy | The classic artisan country loaf |
| 80–85% | Very slack, spreads, needs coil folds | Very open, big holes | Ciabatta-style, weekend showpieces |
| 90%+ | Almost batter, poured into a pan | Extremely open | Focaccia |
Each of these has a dedicated page with tips: 70%, 75%, 80%, 85% and 90%.
How to pick your hydration
Three factors decide the right number for you:
1. Your flour. Strong bread flour (12–13% protein) happily absorbs 75–80%. Whole wheat and rye drink even more water but build weaker gluten, so 65–72% is usually wiser. Weak all-purpose flour starts falling apart around 75%.
2. Your skill. Hydration and difficulty rise together. At 70% you can shape with confidence; at 85% the dough is an exercise in wet-hand origami. Move up in 5-point steps, one bake at a time.
3. Your target bread. A sandwich loaf wants 65–70%. A country loaf with an open crumb wants 75–80%. Focaccia wants 85–95%. Choose the bread first, then the percentage.
How to adjust a recipe’s hydration
The adjustment is one line of arithmetic: for every 100 g of total flour, each percentage point of hydration is 1 g of water.
- To go from 70% to 75% on a 500 g-flour loaf: add 5 × 5 g = 25 g of water.
- To go from 75% to 70%: remove 25 g.
Use the “tweak to” slider on the calculator; it does this for you, including the starter’s hidden water.
Two practical notes when raising hydration:
- Add the water in stages. Autolyse the flour with most of the water, then add the rest in the first folds. Dough accepts water more easily when gluten has relaxed.
- Expect to change your schedule. Wet doughs ferment a little faster and rise more during bulk. Keep an eye on the dough, not the clock.
The three mistakes beginners make with hydration
1. Trusting the recipe’s number. As shown above, starter-inclusive hydration is usually higher than the recipe claims. Use true hydration when comparing recipes or copying a formula.
2. Judging wetness by stickiness. A 70% dough can feel sticky at the start of bulk and silky by the end; stickiness is often fermentation, not water. Judge your dough by how it behaves after folds, not at mixing.
3. Chasing high hydration too early. The internet loves 80%+ loaves with cathedral crumbs. Those bakes are the result of strong flour, a mature starter, and hundreds of loaves of practice. A beautiful 70% loaf beats a collapsed 85% one every time.
Hydration and fermentation
Water speeds up the party. A wetter dough ferments faster because enzymes and yeast move more freely, which is why 80% doughs can over-proof in the time a 65% dough takes to double. If you raise hydration, shorten your bulk slightly and watch for the signs: a puffy, domed, jiggly dough that has grown 50–75% is ready to shape. When in doubt, shape early: an under-proofed loaf is edible and fixable, an over-proofed one is a pancake.
Putting it together
Pick your bread, pick your percentage, weigh everything in grams, and let the calculator do the starter math. Then bake the same recipe twice: once at 70% and once at 75%, and you will feel what the percentage means faster than any article can explain it.
For the next layer, see the sourdough starter guide (feeding ratios and maintenance) or jump straight to troubleshooting when a bake goes sideways.
Frequently asked questions
How do I calculate sourdough hydration?
Divide total water by total flour and multiply by 100. Include the water and flour inside your starter: at 100% starter hydration, half the starter's weight is flour and half is water. For 500 g flour, 350 g water and 100 g starter, that is (350 + 50) ÷ (500 + 50) × 100 = 72.7%.
What does 100% hydration mean in sourdough?
A 100% hydration dough has equal weights of flour and water. The term is also used for starters: a 100% hydration starter was fed equal parts flour and water by weight.
Is 70% hydration good for sourdough?
Yes, 65–70% is the classic beginner range. The dough is firm enough to shape by hand, bakes a tight, even crumb, and is far more forgiving while you learn folds, fermentation and scoring.
What is the best hydration for sourdough bread?
75–80% for a classic open-crumb country loaf with strong bread flour. Beginners should start at 70% and raise hydration one step at a time as their handling skills grow.
Why is my sourdough so sticky even at low hydration?
Stickiness usually comes from under-fermentation, a weak or young starter, or too much whole grain, not from the water alone. Warm the dough, strengthen the starter, and give bulk fermentation more time.
What happens if my dough is too hydrated?
The dough becomes slack, spreads flat, and is hard to shape. You can fix it by adding flour (a tablespoon at a time), doing extra coil folds, or baking it as focaccia in a pan, which needs no shaping at all.