Planning and maths

Hydration and baker's percentages: scale any recipe to the loaf you want

Updated October 2026 · 2 min read

Bakers don't think in grams but in percentages of the flour. Once that clicks, you can scale, shrink and compare any recipe.

Baker's percentages

In baker's percentages the flour is always 100 %. Every other ingredient is given in relation to it. A typical sourdough loaf looks like this:

Ingredient	Baker's percentage
Flour	100 %
Water	68 %
Starter	20 %
Salt	2 %
Total	190 %

Hydration

Hydration is the water in baker's percentage. 68 % hydration means 680 g water for every 1000 g flour. The starter contains flour and water itself, usually in equal parts. If you want to be exact, you count both and call it total hydration.

60–65 %: a stiff dough, easy to shape, tighter crumb. A good place to start.
68–72 %: the usual range for wheat sourdough.
75 % and up: an open crumb with big holes, but stickier and harder to shape.

Whole grain flour and rye absorb more water than white flour. A dough with a lot of whole grain feels stiffer at the same hydration.

Scaling a recipe to your weight

You want 900 g of dough. The baker's percentages add up to 190 %. So the flour is:

900 g ÷ 1.90 = 474 g flour

Everything else follows: 68 % of 474 g is 322 g water, 20 % is 95 g starter, 2 % is 9.5 g salt. Together, 900 g.

Bread loses water in the oven, usually 10–15 % of the dough weight. So 900 g of dough becomes a loaf of just under 800 g.

Common questions

Does the water in the starter count towards hydration?

In many recipes it doesn't – there the hydration refers only to the added water. Others include the starter. With 20 % starter the difference is a few percentage points. What matters is to count the same way when you compare two recipes.

Why do rye breads have such high hydration?

Rye absorbs much more water than wheat and doesn't form a gluten network. Rye doughs at 80 % hydration and above are normal and feel more like a thick paste than a dough.

Why weigh instead of using cups?

A cup of flour weighs anywhere between 120 and 150 g, depending on the flour and how you fill the cup. For water and salt, weighing is more precise and faster. Baker's percentages only work with weights.