Free tool

Sourdough Hydration Calculator

Most recipes list flour and water, but your starter is flour and water too. A 100 g scoop of 100% hydration starter adds 50 g of flour and 50 g of water that simple calculators ignore, and that is enough to shift a dough's hydration by a few percentage points.

This calculator folds the starter back into the totals, so you see your dough's true hydration and the baker's percentage of every ingredient. Reverse mode tells you exactly how much water to add to hit a target.

Your dough

Overall hydration
—

Total flour
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Total water
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Salt
—
Total dough weight
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Baker's percentages

Ingredient Grams Baker's %
Flour (including starter flour)——
Water (including starter water)——
Starter——
Salt——

Runs entirely in your browser. Nothing you type is sent anywhere.

How to use it

  1. 1

    Choose a mode: check the hydration of a recipe you already have, or find the water you need for the hydration you want.

  2. 2

    Enter the flour and water you add to the dough, in grams. Don't include the starter in these two fields.

  3. 3

    Enter how much starter (or levain) goes in and its hydration. If you feed it equal weights of flour and water, that's 100%.

  4. 4

    Set the salt as a percentage of flour. 2% is the classic amount for sourdough.

  5. 5

    Read the overall hydration, total dough weight and baker's percentages. Everything updates as you type.

The math, explained

A starter at hydration h (written as a decimal, so 100% = 1) splits into flour and water like this: starter flour = starter ÷ (1 + h) and starter water = starter − starter flour. At 100% hydration, 100 g of starter is 50 g flour and 50 g water. At 60%, it's 62.5 g flour and 37.5 g water.

Then total flour = flour + starter flour, total water = water + starter water, and hydration = total water ÷ total flour × 100.

Baker's percentages express every ingredient as a share of total flour, which is always 100%. Salt works the same way: salt = total flour × salt % ÷ 100.

Reverse mode solves for the water instead: water to add = total flour × target hydration ÷ 100 − starter water.

Example: 500 g flour, 350 g water and 100 g of 100% hydration starter give 550 g of total flour and 400 g of total water. That's 72.7% hydration, not the 70% you'd get by ignoring the starter. With 2% salt you add 11 g of salt, for 961 g of dough.

Frequently asked questions

Should I include the starter when calculating sourdough hydration?

Yes. Starter is flour and water, so leaving it out understates hydration. With 20% of a 100% hydration starter, the difference is roughly 2–4 percentage points: small on paper, but noticeable in how sticky the dough feels.

What is a good hydration for a beginner sourdough loaf?

Around 65–72% is forgiving: the dough holds its shape, is easy to handle and still bakes a nicely open crumb. Once shaping feels comfortable, raise it in steps of 2–3%. Whole-wheat and rye flours absorb more water, so they can take a higher hydration and feel the same.

How do I find my starter's hydration?

Divide the water you feed by the flour you feed and multiply by 100. Feeding 50 g flour and 50 g water is 100%; 50 g flour and 30 g water is 60%. If you always feed in the same proportions, your starter settles at that hydration after a few feeds.

Is salt counted in hydration?

No. Hydration only compares water to flour. Salt has its own baker's percentage, usually 1.8–2.2% of total flour. Liquids such as milk do contain water (milk is roughly 87% water), so bakers sometimes count them proportionally, but salt never counts.

Why does my dough feel wetter than its hydration suggests?

The flour matters as much as the number. White and lower-protein flours absorb less water than strong bread flour or whole grains, so the same 75% can feel slack with one flour and firm with another. Warm dough and over-fermentation also make dough feel wetter.

More sourdough calculators

Keep reading

Browse all sourdough guides on the Boulie blog →