Sourdough Calculator
This calculator works out your dough's hydration percentage from flour and water weight, or the reverse — how much water to add for a target hydration.
It also scales starter amounts so your levain matches the size of your final dough.
Hydration is the single number most sourdough recipes are built around, since it determines whether a dough handles like a stiff, easy-to-shape ball or a slack, sticky mass that needs different folding and shaping techniques.
How to Use the Sourdough Calculator
Reference Values
The Science Behind It
Hydration is the ratio of water weight to flour weight, expressed as a percentage. Higher hydration doughs produce a more open, irregular crumb and a chewier crust, but they're harder to shape. Lower hydration doughs are easier to handle and produce a tighter crumb. Source: King Arthur Baking.
Wild yeast and lactic acid bacteria in a sourdough starter ferment more slowly than commercial yeast, which is why sourdough recipes typically call for longer bulk fermentation and proofing times than a same-day yeasted loaf.
The Bread Baker's Guild of America, a professional organization for artisan bakers, teaches hydration as the first variable to master before adjusting fermentation time or oven temperature, since it affects nearly every other part of the process.
Where This Shows Up
Home bakers troubleshooting a dense or gummy loaf often start by checking hydration, since underhydrated dough traps less steam and produces a tighter, heavier crumb than intended.
Bakers adapting a recipe to a new flour brand frequently need to adjust hydration slightly, since different flours absorb water differently based on their protein content and milling process.
Sourdough baking communities and forums frequently reference hydration percentage as shorthand when sharing or comparing recipes, making it a useful figure to calculate even for bakers who aren't precisely measuring every batch.
A Worked Example
Say you're mixing a loaf with 500g of flour and 350g of water. Divide 350 by 500 and multiply by 100 to get 70% hydration — a workable, medium-wet dough suited to a standard sandwich loaf. If you wanted a wetter, more open-crumb artisan loaf at 80% hydration instead, you'd need 400g of water for the same 500g of flour, an extra 50g that changes how the dough handles noticeably.
Lean vs Enriched Sourdough Hydration
| Lean Dough (bread, boules) | Enriched Dough (with milk, egg, butter) | |
|---|---|---|
| Typical hydration | 65-85% | 50-65% |
| Handling | Wetter, requires folding technique | Softer but easier to shape |
| Crumb result | Open, irregular holes | Tighter, more even crumb |
Common Mistakes
- Forgetting to include the starter's own water content when calculating total dough hydration, which understates the true percentage.
- Using cold tap water without accounting for how it slows fermentation compared to room-temperature water.
- Assuming every all-purpose flour absorbs water identically, when protein content varies meaningfully between brands.
- Judging dough readiness by rise time alone rather than checking hydration first, since a dough that seems slow to rise is often just wetter than the baker expects.
- Ignoring how ambient kitchen humidity can affect flour's moisture content over time, subtly changing how much water a dough actually needs to hit a target hydration.
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Frequently Asked Questions
What is a good hydration percentage for beginners?+
60–65% is easier to shape and forgiving for a first sourdough loaf.
How much starter should I use?+
Most recipes use 10–20% of the flour weight in mature starter, though this varies by recipe and desired fermentation speed.
Does hydration include the water in the starter?+
Yes, a proper hydration calculation should include all water in the dough, including what's contributed by the starter itself.
Why do wetter doughs need more skill to shape?+
High-hydration dough is slacker and stickier, making it harder to build tension during shaping without it spreading or tearing — a skill that typically comes with practice.
Can I use this calculator for enriched sourdough recipes?+
Yes, though you'll want to count any milk, egg, or butter as part of the total liquid contribution when calculating true hydration.
Does starter maturity affect the hydration calculation?+
No, hydration math stays the same regardless of starter maturity — maturity affects rise speed and flavor, not the underlying flour-to-water ratio.