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Sourdough Levain Calculator

Enter your total flour and levain percentage to size the levain build.

Result

200 g
100 g
20 g

How it is calculated

Inputs are the recipe's total flour in grams and the levain percentage. The tool treats that percentage as the total weight of the levain: levain = flour × pct / 100. The build is assumed to be 100% hydration, so flour and water are equal halves: flour = water = levain / 2. The starter seed is seed = levain × 0.10, and it is listed on top of the flour and water, not subtracted from them. If the percentage is left blank it defaults to 20. All figures are rounded to whole grams, so on small batches the parts can differ from the total by a gram. The tool does not remove the levain's flour from the main dough, so adjust the final-dough flour and water yourself.

Worked example

A recipe with 1,000 g of total flour and a 20% levain. Levain: 1000 × 20 / 100 = 200 g. At 100% hydration, flour and water are 200 / 2 = 100 g each. Seed: 200 × 0.10 = 20 g of mature starter. So you mix 100 g flour, 100 g water and 20 g starter, and let it ripen before mixing the final dough. At 450 g flour and 15% the levain would be 67.5, shown rounded as 68 g.

Try this example →

Common mistakes

  • Entering the levain flour weight instead of the total recipe flour. The tool multiplies whatever you enter by the percentage.
  • Reading the levain figure as the flour in the levain. It is the whole levain weight (flour plus water); the flour alone is half of it.
  • Using the tool for a hydration other than 100%. The flour and water split is always equal, so a stiff or liquid levain needs adjusting by hand.
  • Forgetting that the levain's flour and water are part of the final dough. If the recipe's hydration should stay the same, subtract them from the main-dough flour and water.
  • Rounding up the seed to a big spoonful. Seed is only 10% of the levain weight, and a larger seed ferments faster.

About this calculator

A sourdough levain is a small portion of the final dough, fermented separately with flour, water and a spoonful of mature starter before it's mixed into the main dough. Bakers plan it using baker's percentages: a common build makes a levain whose total weight is roughly 15–25% of the recipe's total flour, at 100% hydration (equal weights of flour and water, so each is half of the levain), inoculated with a starter "seed" of about 10% of the levain's weight.

Sizing this correctly matters for timing as much as flavor — a levain built too small or too cold ferments slowly and may underperform the main dough's rise, while an oversized or overly ripe levain turns a loaf sour and slack. Working backward from total flour and the target levain percentage tells a baker exactly how much flour, water and starter seed to combine, and when to start the build relative to the final mix.

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Comments (1)

  • Editorial team

    The three amounts follow a 1:5:5 starter to flour to water ratio, a proportion often used for slower, cooler builds. Because the starter is listed on top of the flour and water, the parts add up to 110 g for the 100 g headline figure, so expect a slightly larger levain than the first number. What ratio and room temperature do you build yours at?

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