Sourdough hydration confuses more bakers than almost any other topic. Part of the confusion is that sourdough introduces a variable that yeasted bread doesn’t have: a starter that itself contains both flour and water. Ignore that contribution and your hydration numbers are wrong from the start.
This guide walks through everything — how to calculate sourdough hydration correctly, where to begin as a new baker, how to progress toward higher hydration loaves, and what to do when things go wrong.
Why Sourdough Hydration Is Different
In a simple yeasted bread, hydration is just water divided by flour. In sourdough, you have a third ingredient — the starter — that contains both flour and water in a fixed ratio. That ratio depends on how you maintain your starter.
A starter maintained at 100% hydration is fed equal weights of flour and water (1:1 by weight). So 100g of a 100%-hydration starter contains 50g flour and 50g water.
A stiff starter at 50% hydration contains two parts flour to one part water: 100g of stiff starter = 67g flour and 33g water.
If you don’t account for the starter’s contribution, you’re calculating hydration against the wrong flour and water totals — which makes it impossible to reliably reproduce results or troubleshoot problems.
How to Calculate Sourdough Hydration Step by Step
Here is the method used by professional bakers:
- Determine your starter’s hydration ratio
- Break the starter into its flour and water components
- Add those to the recipe’s flour and water totals
- Divide total water by total flour
Example with a 100%-hydration starter:
- Starter: 100g (50g flour + 50g water)
- Additional flour: 450g
- Additional water: 310g
- Total flour: 50 + 450 = 500g
- Total water: 50 + 310 = 360g
- Hydration: 360 ÷ 500 × 100 = 72%
Without accounting for the starter, you might divide 310 by 450 and get 69% — a meaningful difference that compounds across recipe adjustments.
Starter hydration conversion table:
| Starter Type | Starter Hydration | Per 100g Starter: Flour | Per 100g Starter: Water |
|---|---|---|---|
| Stiff starter | 50% | 67g | 33g |
| Medium starter | 75% | 57g | 43g |
| Liquid starter | 100% | 50g | 50g |
| Very liquid starter | 125% | 44g | 56g |
Recommended Hydration Levels by Skill
The table below gives you a practical roadmap from beginner to advanced:
| Level | Hydration Range | What to Expect | Key Techniques |
|---|---|---|---|
| Beginner | 65–70% | Firm, workable, easy to shape | Basic fold-and-shape |
| Intermediate | 70–78% | Noticeably stickier, requires technique | Stretch and fold, pre-shape + bench rest |
| Advanced | 78–85% | Slack, demands confident handling | Coil folds, cold retard, tight final shape |
| Expert | 85–100%+ | Extremely extensible, structure from technique only | Lamination, gentle shaping, Dutch oven |
Starting Out: 65–70% Hydration
If you’re baking sourdough for the first time, start between 65% and 70% hydration. Here’s why this range is the right learning ground:
The dough holds its shape. At 65–70%, the dough has enough structure to be shaped without spreading flat, which means you get useful feedback on whether your shaping technique is working.
You can feel gluten development. Building tension in a lower-hydration dough gives you a clear physical reference — the dough tightens, the surface becomes smooth, and you can feel the structure you’re creating. At 85%, that feedback is much harder to read through all the stickiness.
Fermentation is more forgiving. Over-fermented dough at 68% still has enough structure to produce an acceptable loaf. The same mistake at 82% often results in a pancake.
A practical beginner formula (1 loaf):
- 450g bread flour
- 50g whole wheat flour (10% whole grain adds flavor and fermentation activity)
- 100g starter (100% hydration)
- 335g water
- 10g salt
Total flour: 450 + 50 + 50 (from starter) = 550g Total water: 335 + 50 (from starter) = 385g Hydration: 385 ÷ 550 × 100 = 70%
Moving to Intermediate Hydration (70–80%)
Once you can reliably shape a 70% dough into a tight boule, hold its shape through a cold proof, and score it confidently, you’re ready to push higher.
At 72–78%, the dough becomes noticeably stickier and more extensible. It will try to spread on the bench. These are the adjustments to make:
Add stretch and fold sets. During the first 2–3 hours of bulk fermentation, perform 4–6 sets of stretch and folds, spaced 30 minutes apart. Each set builds gluten strength without degassing.
Use coil folds instead of slap-and-fold. Coil folds (lifting the dough from the center and letting both ends fold underneath) are gentler and more effective for wetter doughs.
Pre-shape and rest. After bulk fermentation, pre-shape into a rough round and let the dough rest uncovered on the bench for 20–30 minutes. This bench rest allows surface tension to build and relaxes the gluten so the final shape is easier to execute.
Cold retard. After final shaping, place the banneton in the fridge for 8–16 hours. Cold retarding firms the dough significantly, making it easier to score, and dramatically improves crust flavor.
Advanced Sourdough at 80–100%+
Open crumb sourdough — the kind with large, irregular holes and a translucent crumb structure — typically lives above 80% hydration. But hydration alone doesn’t create open crumb. The three factors that matter most are:
- Fermentation timing: The dough must be adequately proofed but not over-proofed. Under-fermented dough is too tight and dense; over-fermented dough collapses in the oven.
- Shaping technique: High-hydration doughs need to be shaped with minimal degassing. The goal is to build surface tension without pressing out the gas bubbles you’ve spent 6 hours developing.
- Baking vessel: A Dutch oven or combo cooker traps steam in the first 20 minutes of baking, allowing maximum oven spring. Without it, even a perfectly fermented high-hydration loaf will spread rather than rise.
At 85%+, lamination can help. After the first hour of bulk fermentation, wet the bench, pour the dough out flat, and gently stretch it into a large thin sheet without tearing. Fold it back onto itself like a letter. This technique aligns gluten strands and creates the structure that makes extreme open crumb possible.
How Starter Hydration Affects Flavor
Starter hydration isn’t just a calculation variable — it’s a flavor lever.
Stiff starter (50–60% hydration): Ferments more slowly, produces more acetic acid. The result is a tangier, more complex sourness — the kind associated with San Francisco sourdough.
Liquid starter (100–125% hydration): Ferments faster, produces more lactic acid. The result is a milder, creamier sourness, closer to yogurt than vinegar.
This means you can influence the flavor profile of your loaf by adjusting starter hydration independently of dough hydration. A stiff starter in a 72% dough produces a different flavor than a liquid starter in the same dough — without changing any other variable.
Troubleshooting Sourdough Hydration Problems
Dough spreads flat after shaping: This usually means one of two things — the dough is over-fermented (the gluten has broken down and can no longer hold structure) or the hydration is too high for the current gluten development. Try reducing bulk fermentation time by 15–20% on the next bake before reducing hydration.
Dense, gummy crumb: The most common cause is under-fermentation — the yeast didn’t produce enough gas during bulk. This can happen at any hydration level. Increase bulk fermentation time (look for 50–75% volume increase with visible bubbles on the surface and sides of the container) before adjusting water.
Calculations don’t add up: Go back and check whether you accounted for the starter’s flour and water contribution. This is the single most common source of calculation errors in sourdough. Also verify that your starter hydration ratio is what you think it is — a starter that’s been fed unevenly over time can drift from its nominal hydration.
Dough sticks to the banneton: This isn’t a hydration problem — it’s a preparation problem. Rice flour (not wheat flour) in the banneton prevents sticking reliably. Linen liners also help.
The Bigger Picture
Hydration percentage in sourdough is a useful tool for reproducibility and communication — but it’s not a score. A 68% sourdough made with excellent technique, a well-maintained starter, and good fermentation timing will outperform a carelessly made 82% loaf every time.
Build your technique at lower hydrations. Learn what good bulk fermentation looks and feels like. Practice shaping until it’s confident and consistent. Then push the hydration higher — and the numbers will start making sense in a physical, tactile way that reading alone can’t teach.