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Sourdough calculator

Sourdough Calculator

Set your loaf size, hydration and starter, and get a sourdough bread recipe you can weigh out.

A sliced sourdough loaf with an open crumb
g

Defaults follow The Perfect Loaf's beginner's sourdough: two 900 g loaves at 72% hydration.

%
%
%

9.5% of the flour (98 g) is already in the starter.

Starter hydration100%
%

100% is a 1:1 starter (equal flour and water). Stiff starters are around 50–60%.

Your dough

Makes 2 loaves, 900 g (31.7 oz) of dough each.

Total dough
1800 g63.5 oz
Per loaf
900 g31.7 oz
Hydration
72%incl. starter

What the dough is made of, by weight.

  • Flour90.5%bread flour · ≈ 7 3/4 cups + 1 tbsp937 g33.1 oz
  • Water62.5%≈ 2 3/4 cups647 g22.8 oz
  • Sourdough starter19%active, 100% hydration: 98 g flour + 98 g water · ≈ 3/4 cup + 1 tbsp197 g6.9 oz
  • Salt (table)1.8%≈ 1 tbsp19 g0.66 oz
Total formula, starter included
IngredientWeightBaker's %
Total flour1036 g100%
Total water746 g72%
Salt19 g1.8%
Prefermented flour98 g9.5%

Ingredient percentages are of the total flour, including the flour in the starter. Cups and spoons are approximate, based on King Arthur Baking's ingredient weights; a kitchen scale gives the best results.

How it works

A sourdough recipe is written in baker's percentages of the total flour, and the starter is part of the dough: its flour counts as flour and its water counts as water. So the calculator first works out the total flour from the dough weight you want, then takes the starter's share back out:

total flour = total dough ÷ (1 + hydration% + salt%)

starter flour = starter ÷ (1 + starter hydration%)

The flour you add is total flour minus the starter's flour, and the water you add is total water minus the starter's water.

Worked example

A sourdough loaf cut open to show its airy crumb
One 1,000 g loaf
  1. One 1,000 g loaf at 75% hydration and 2% salt, with 20% starter at 100% hydration.
  2. Total flour = 1,000 ÷ (1 + 0.75 + 0.02) = 1,000 ÷ 1.77 = 565 g.
  3. Starter = 565 × 0.20 = 113 g, which is 56.5 g flour and 56.5 g water.
  4. Flour to add = 565 − 56.5 = 508.5 g. Water to add = 565 × 0.75 − 56.5 =367.2 g. Salt = 565 × 0.02 = 11.3 g.
  5. Check: 508.5 + 367.2 + 113 + 11.3 = 1,000 g.

Prefermented flour is the share of the total flour that is already fermenting in the starter when you mix. It is the starter percentage divided by (1 + starter hydration), so a 20% starter at 100% hydration means 10% prefermented flour. It is the most useful number for comparing recipes that use starters of different hydrations.

The default recipe is The Perfect Loaf's beginner's sourdough bread, converted to baker's percentages: 1,800 g of dough for two loaves, 72% hydration, 1.8% salt and a 100% hydration levain of about 19% of the flour.

FAQ

Does the hydration include the water in the starter?

Yes. A sourdough starter is half flour and half water at 100% hydration, so this calculator counts its flour and water in the totals. Hydration here is all the water divided by all the flour, the way The Perfect Loaf and most bakers' formulas present it. If you left the starter out, a 72% dough with a 20% starter would really be closer to 70%.

How much starter should I use?

Most sourdough breads use a starter (or levain) of about 10–25% of the total flour weight. The Perfect Loaf's beginner's loaf uses about 19%. Less starter gives a slower rise and more time to build flavor; more starter makes the dough ferment faster, which helps in a cool kitchen.

What hydration is best for a first sourdough loaf?

Around 70–75% is a good place to start with bread flour. The Perfect Loaf's beginner's recipe is 72%. Whole wheat and rye flours absorb more water, so doughs with a lot of them can take a higher hydration and still feel the same.

What if my starter isn't 100% hydration?

Open "Starter hydration" and set your starter's hydration. A stiff starter fed 1 part water to 2 parts flour is 50%; a liquid one fed 5 parts water to 4 parts flour is 125%. The calculator splits the starter into its flour and water and adjusts the flour and water you add, so the total hydration stays where you set it.

Can I measure sourdough ingredients in cups?

You can, but a scale is much more reliable. A cup of flour can weigh 110–150 g depending on how it is scooped. The cup amounts here use the King Arthur Baking ingredient weight chart (120 g per cup of bread flour, about 234 g per cup of 100% hydration starter).

Sources