WhiskMath

Sourdough Hydration Calculator

Get the exact water to add for any target hydration — accounting for the flour and water already in your starter.

g
%
g
%
Water to add
650 g
for 75% dough
Salt
20 g
2% of total flour
Total dough
1770 g
finished weight
  • Total flour (with starter): 1000 g — total water: 750 g.
  • Your starter is 20% of total flour (baker's percentage).
  • A 100%-hydration starter is half flour, half water by weight — both are counted in the totals.
  • Hold back a little water and add it during mixing if the dough feels too slack.
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How to use this calculator

  1. Enter your flour weight

    Type the weight of flour you are adding to the dough, in grams.

  2. Set your target hydration

    Enter the hydration percentage you want for the finished dough — for example 70% for an everyday artisan loaf.

  3. Enter your starter and salt

    Add your starter weight in grams and the salt percentage, typically around 2%.

  4. Read the water to add

    The calculator subtracts the water already in your starter and shows exactly how much water to add, plus the total dough weight and baker's percentages.

Recommended gear

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Escali Primo Digital Kitchen Scale

Sourdough hydration is pure weight math — an accurate gram scale is non-negotiable.

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King Arthur All-Purpose Flour

A consistent-protein flour keeps water absorption predictable from one bake to the next.

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Sourdough hydration levels and crumb style

HydrationStyleCrumb
65%Sandwich loafTight, even, easy to slice
70%Everyday artisanModerately open, balanced
75%Open crumbOpen and irregular, crisp crust
80%+Advanced / ciabatta-styleVery open, slack and sticky dough

Higher hydration generally means a more open crumb but a harder-to-handle dough.

Tips & best practices

  • Always weigh your ingredients in grams — hydration math only works by weight, never by volume.
  • Keep your starter at a consistent 100% hydration so the calculation stays predictable bake to bake.
  • Hold back about 5% of the water at first and add it during mixing only if the dough feels too tight.
  • Whole grain flours drink more water — expect to nudge hydration up when you add rye or whole wheat.
  • Higher hydration needs stronger gluten development — use stretch-and-folds rather than a long initial knead.
  • Note the hydration that works best for your flour and kitchen; it becomes your reliable house dough.

Frequently asked questions

What is hydration in sourdough baking?
Hydration is the weight of water in a dough expressed as a percentage of the weight of flour. A dough with 1,000 grams of flour and 750 grams of water is at 75% hydration.
How do I calculate sourdough hydration?
Divide the total water by the total flour and multiply by 100. The key is to include the flour and water inside your starter in those totals, which this calculator does automatically.
Does the starter count toward hydration?
Yes. A starter at 100% hydration is half flour and half water by weight, so a 200-gram starter adds 100 grams of flour and 100 grams of water to your totals. Ignoring it throws the final hydration off.
What hydration should a beginner start with?
Around 65 to 70% is a forgiving range for beginners. It produces a workable dough that holds its shape, while still giving an open, tender crumb as your shaping improves.
What does higher hydration do to sourdough?
Higher hydration, roughly 75% and above, generally gives a more open, irregular crumb and a crisp crust, but the dough is slacker and stickier to handle. Lower hydration gives a tighter, more uniform crumb that is easier to shape.
How much salt should I use in sourdough?
About 2% of the total flour weight is standard. Salt strengthens the gluten and controls fermentation as well as adding flavor, so it is worth weighing rather than estimating.
Why does my dough feel wetter than the hydration suggests?
Different flours absorb water differently — whole grain and high-protein flours take up more than white flour. Use the calculated water as a starting point and hold back a little to add during mixing if the dough feels too slack.
Can I use this calculator for a stiff starter?
This calculator assumes a 100% hydration starter, which is the most common. For a stiffer starter, the flour-to-water split inside it changes, so the result would need adjusting — keeping a 1:1 starter is the simplest path.

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Sources: Tartine Bread by Chad Robertson; Standard baker's percentage method for hydration.

Results are estimates for informational use. For food safety, always confirm meat doneness with a thermometer against current USDA guidance. WhiskMath does not provide medical or dietary advice.