Sourdough Hydration Calculator
The starter raises true hydration above the stated figure.
Work out Sourdough Hydration. The starter raises true hydration above the stated figure. Free, with no account and nothing to install.
100% means equal flour and water by weight
Total dough weight
1,920 g
960 g per loaf · true hydration 72.7%
A starter is itself flour and water, so it raises the real hydration above the stated figure — here 70% on paper and 72.7% in the bowl. That gap is why a dough at a "70% hydration" recipe can handle like one at 73%, and it grows with the amount of starter used. Baker's percentages are always of the flour weight, never of the total, which is why they can add to more than 100%.
How the Sourdough Hydration Calculator works
Baker's percentages for a sourdough, with true hydration calculated by splitting the starter back into its own flour and water. That gap is why a dough at 70% on paper can handle like one at 73%.
Also known as: bakers percentage calculator · what is true hydration in sourdough · bread dough water to flour ratio · sourdough recipe scaler
Baker's percentages, and why they exceed 100
Every ingredient is expressed as a percentage of the flour weight, and the flour is always 100%. Water at 70%, salt at 2% and starter at 20% describes a dough completely, and the percentages add to 192 — which is correct rather than an error.
The point is that it scales. The same set of percentages describes one loaf or fifty, and a baker changing batch size changes only the flour weight. It is why the notation survived from professional bakeries into home baking.
It also makes recipes comparable. Two sourdough recipes at 75% and 65% hydration differ in a way that is immediately legible in percentages and completely obscured when both are written as cups and grams of specific quantities.
True hydration and the starter's hidden flour
A sourdough starter is itself flour and water. A 100% hydration starter is half of each by weight, so 200 g of starter contributes 100 g of flour and 100 g of water that the stated percentages do not account for.
Which means the real water-to-flour ratio is higher than the recipe says. A dough written as 70% hydration with 20% of a 100% starter has a true hydration of about 72.7%, and the gap grows with the amount of starter used.
That difference is why a dough at a nominal 70% can handle like one at 73% — noticeably slacker than expected. A stiff starter at 50% hydration carries proportionally more flour and raises true hydration much less, which is one reason some bakers prefer them.
Where a sourdough actually goes wrong
Most dense loaves are an under-active starter or under-proofing rather than a hydration problem. A starter should reliably double within four to six hours of feeding before it is used, and one that does not is not ready however good the recipe is.
Proofing is judged by the dough rather than the clock, because temperature changes fermentation rate enormously. The poke test — a floured finger leaving a slight indent that springs back slowly — is more reliable than any stated time.
A cold overnight retard in the refrigerator is the single highest-return change in a home routine. It slows fermentation, develops more flavour through longer enzymatic action, and firms the dough enough to score cleanly, which is where most home loaves lose their appearance.
Where to go next
The Sourdough Hydration question rarely arrives on its own. These are the ones that usually come with it:
- Baking Conversion Calculator — A cup of honey outweighs a cup of flour nearly three to one.
- Oven Temperature Converter — Your oven is probably not the temperature it claims.
- Serving Size Calculator — Meat shrinks, rice swells — buy by the raw weight.
- Ring Size Calculator — Finger measurement to US, UK, EU and Japanese sizes.
Frequently asked questions
What is baker's percentage?
Every ingredient expressed as a percentage of the flour weight, which is always 100%. It means a recipe scales to any batch size, and it is why the percentages can add to more than 100.
What is true hydration?
The real water-to-flour ratio once the starter is split into its own flour and water. A 100% hydration starter at 20% of the flour weight lifts a stated 70% dough to about 72.7%.
What hydration should I use?
Lower is easier to handle: 65 to 70% for a first sourdough, 75 to 85% for an open crumb once you can manage a slack dough. Flour matters too — strong bread flour absorbs more than plain.
How much salt should bread have?
Conventionally 1.8 to 2.2% of the flour weight. Below that the dough slackens and the flavour falls flat; above it fermentation slows noticeably.
How much starter should I use?
Commonly 10 to 20% of the flour weight. More starter ferments faster and gives a sharper flavour; less takes longer and develops more complexity. Ambient temperature changes the timing more than the quantity does.
Does starter hydration matter?
Yes, for the true hydration figure. A 100% starter is equal flour and water; a stiff starter at 50% carries proportionally more flour, so it raises the real hydration less.
Why is my sourdough dense?
Most often an under-active starter or under-proofing. A starter should reliably double within four to six hours of feeding before it is used for bread.
How do I know when the dough is proofed?
The poke test: a lightly floured finger pressed in should spring back slowly and leave a slight indent. Springing back fast means under-proofed; not springing back at all means over.
What does autolyse do?
Resting flour and water before adding salt and starter lets the flour hydrate and gluten begin forming without kneading. It makes a slack dough noticeably easier to handle.
Does flour type change the hydration?
Considerably. Strong bread flour absorbs more water than plain, and wholemeal more again. The same percentage handles very differently between them, which is why the number is a starting point.
Why does my crust go soft?
Steam trapped after baking. Cooling on a wire rack rather than a solid surface lets moisture escape, and finishing the bake with the oven door ajar helps further.
Can I refrigerate the dough overnight?
Yes — a cold retard slows fermentation, develops more flavour and makes the dough much easier to score. It is one of the highest-return changes in a home sourdough routine.
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