Sourdough Hydration Calculator

Most sourdough recipes print a hydration number, 70%, 75%, 80%, but that figure usually counts only the water and flour added at mixing, ignoring the starter, which is itself flour and water in one. Your starter is a preferment, flour and water that fermented overnight. Mix 500 g of flour, 350 g of water and 100 g of a 100% hydration starter, and the true hydration is not 70%: the starter adds 50 g of flour and 50 g of water, so the real totals are 550 g of flour and 400 g of water, 72.7% true hydration. This calculator fixes it: enter your recipe flour, water, starter weight and starter hydration, and it splits the starter into its flour and water parts, totals everything, and reports the true hydration for judging dough. You also get baker's percentages, the universal language of bread formulas, plus total dough weight and handling notes matched to your hydration band. Whether you keep a stiff 60% starter, a classic 100% one or a liquid 125% one, or blend bread flour with whole wheat and rye, the maths stays honest from autolyse through bulk fermentation to the final crumb.

Last updated: October 22, 2026

Written by Ateeq Fareedi · Last updated October 22, 2026

The formula

Starter flour = starter weight ÷ (1 + starter hydration as a decimal)
Starter water = starter weight − starter flour
Total flour = recipe flour + starter flour
Total water = recipe water + starter water
True hydration = total water ÷ total flour × 100
Baker's percentage = ingredient weight ÷ total flour × 100

A worked example

Try 500 g flour, 340 g water and 100 g of 100% hydration starter with 10 g of salt: the starter splits into 50 g flour and 50 g water, so totals are 550 g flour and 390 g water, a true hydration of 70.9%. Water reads 70.9%, starter reads 18.2% and salt reads 1.8% in baker's percentages, and the finished dough weighs about 950 g.

More about the Sourdough Hydration Calculator

Why true hydration beats the number on the recipe card

Hydration is the most quoted number in sourdough, and the most misunderstood. A recipe that says “75% hydration” almost always means (recipe water ÷ recipe flour) × 100, which treats the starter as if it were pure flavour and zero moisture. In reality a 100% hydration starter is half flour, half water: 150 g of it quietly adds 75 g of each to your dough. Skip that contribution and the number on screen will not match the dough in your hands, which is why two bakers following the “same” 75% recipe can end up with completely different doughs.

True hydration counts everything: the flour and water you add at mixing plus the flour and water already inside the starter. This calculator does that split for you, whatever your starter's hydration is, 60% stiff, 100% classic, 125% liquid, and reports the number that experienced bakers actually use when they judge whether a dough will behave. Browse the rest of the <a href="/cooking-recipes/">Cooking & Recipes calculators</a> for recipe scaling, portion planning and temperature guides.

Reading your number: hydration bands and what they mean

Below about 65%, dough feels firm and dry, barely tacky, easy to shape, forgiving of beginners, and it produces a tight, even crumb like a sandwich loaf or bagel. From roughly 65% to 72% you are in the classic artisan zone: the dough is soft and slightly sticky, it shapes with a light touch of flour, and it rewards you with an open but manageable crumb. This is where most first timers should live.

From 72% to 80%, dough gets genuinely slack: you will be wetting your hands, reaching for a bench scraper, and using coil folds instead of aggressive kneading, but the payoff is wide, irregular holes and a thin, crackling crust. Above 80% you are in ciabatta territory, where the dough is closer to poured than shaped. Each band ferments faster than the one below it, so higher hydration doughs need closer watching during bulk fermentation, not longer proofs.

Flour, starters and the variables that shift the feel

Hydration is only half the story, absorption is the other. Whole wheat and rye flours drink far more water than white bread flour, so a 75% whole wheat dough feels like a 65% white flour dough. If you blend flours, expect the same hydration number to feel drier, and resist the urge to chase a wetter number on paper: go by the dough. Climate matters too, humid kitchens effectively raise hydration, and a dough mixed in August in a warm kitchen behaves very differently from the same formula in a cool January.

Your starter's hydration shifts the result more than most bakers expect. A stiff 60% starter carries less water per gram than a liquid 125% starter, so swapping one for the other without recalculating changes the dough's true hydration by several points. That is exactly what this calculator is for: tell it how you actually feed your starter and it folds the real flour and water contribution into every total.

Dialing in a target hydration

Sometimes you want a specific number, you are converting a recipe, or you found a crumb you love and want to reproduce it. Enter a target hydration and the calculator tells you exactly what to change: if the target is above your current hydration, it gives you the grams of water to add; if below, the grams of flour to add (water already in the dough cannot be removed). Add water gradually and mix between additions, a technique bakers call bassinage, because dough absorbs water slowly and you can always add more, but you cannot take it back.

One caution: when you raise hydration by adding water after the fact, keep the salt and starter percentages in mind. The calculator's baker's percentages are computed on final totals, so after an adjustment, re check that the salt still reads around 1.8 to 2.2% of total flour. That is the range where flavour is seasoned without slowing fermentation.

Troubleshooting: when the maths is right but the dough is wrong

Sticky does not always mean wet. A dough that is correctly hydrated but under developed feels just as tacky as a high hydration one, because the gluten network has not organised yet. If your hydration is in the classic range and the dough still spreads everywhere, try stronger gluten development, more coil folds, a longer autolyse, before adding flour.

Conversely, if the dough is tearing and stiff even though the number looks reasonable, check your flour blend: high proportions of whole wheat or rye can make a 75% dough feel like concrete. And if the dough handles beautifully in winter but collapses in summer, it is not your technique, warmer, more humid conditions genuinely speed fermentation and soften dough, so pull back the water by a couple of percent or shorten the bulk ferment.

How to use the Sourdough Hydration Calculator

Weigh your recipe flour, recipe water and starter in grams.
Enter your starter's hydration, 100% if you feed it equal flour and water.
Optionally set a target hydration and salt % to get adjustment amounts.
Click “Calculate hydration” and read true hydration, baker's percentages and handling notes.

Frequently asked questions

What hydration is best for sourdough beginners?

Aim for 68 to 72% true hydration. In that band the dough is soft but shapeable with a little flour, it holds its structure, and it still gives an open, attractive crumb. Very high hydration (75%+) looks exciting online but punishes beginners, the dough is slack, sticky and hard to read during fermentation. Master the 70% range first; you can chase open crumb later once shaping feels natural.

Why is my calculated hydration different from the recipe's number?

Because most recipes calculate hydration as (recipe water ÷ recipe flour) × 100 and ignore the starter. Your starter is flour and water, so it pushes both totals up, a 100 g starter at 100% hydration adds 50 g of flour and 50 g of water, which typically raises the true hydration 2 to 3 points above the recipe's figure. This calculator gives you the true number, which is what actually governs how the dough behaves.

What does a 100% hydration starter mean?

It means you feed the starter with equal weights of flour and water, for example 20 g of old starter, 50 g of flour and 50 g of water. The 100% describes water as a percentage of flour, the same baker's percentage logic the calculator uses for your dough. A stiff starter is usually around 60% (more flour than water) and a liquid starter around 125% (more water than flour), the calculator handles any of them.

Does salt count toward hydration?

No. Hydration is strictly water versus flour. Salt is tracked separately as a baker's percentage of total flour, and the standard range is 1.8 to 2.2%. That is why the calculator asks for salt % as an optional extra: it shows the salt in the baker's percentage readout and includes it in the total dough weight, but it never enters the hydration calculation.

Can I use this with a stiff or liquid starter?

Yes, the starter hydration field accepts anything from 0% to 500%, and the split maths (starter flour = starter weight ÷ (1 + starter hydration)) works at any level. A 100 g stiff starter at 60% hydration contributes 62.5 g of flour and 37.5 g of water, while 100 g of liquid starter at 125% contributes 44.4 g of flour and 55.6 g of water. Just enter how you actually feed your starter.

How do I raise hydration without making the dough unworkable?

Hold back 5 to 10% of the recipe water, mix the dough to a shaggy mass, then add the reserved water in small splashes over the first hour, mixing each in before the next (bassinage). Dough absorbs water slowly, so this lets gluten develop on a manageable dough first. Also try raising hydration only 2 to 3 points per bake, your hands learn the feel of each band, and jumping straight from 70% to 80% is where most doughs get ruined.

How do I calculate sourdough hydration?

Divide water weight by flour weight and multiply by 100. With 350 g water and 500 g flour, hydration is 70%. Beginners should start at 65 to 70%; above 75% gets sticky and hard to handle. Include the water and flour in your starter for precise baker's percentages.

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