Sourdough Clock

Levain Build Calculator: How Much to Build for a Recipe

By Tam Vu · Updated

On this page
  1. The math
  2. Worked example
  3. Starter or levain?
  4. Timing
  5. Sources

A levain is a portion of starter built up for one bake: you feed a little of your starter with flour and water the day before, and use the result in the dough. A recipe usually gives the levain as a percent of the flour. This calculator turns that into grams, then into the starter, flour and water to mix.

Levain for my recipe

The percentage and ratio are examples. Use your recipe's.

The math

  1. Levain needed = flour in the dough × levain % ÷ 100.
  2. Total to mix = levain needed + the extra you keep back for your next starter.
  3. One part = total to mix ÷ (starter part + flour part + water part). Then starter = one part × starter part, flour = one part × flour part, water = one part × water part.
  4. Flour and water inside the levain. A starter at hydration H% holds starter × 100 ÷ (100 + H) flour and starter × H ÷ (100 + H) water. Add the fresh flour and water to get the levain's totals.

Worked example

500 g of flour in the dough, a levain at 20% of the flour, a 1:2:2 feed and a 100% starter. These numbers are examples.

  • Levain needed: 500 × 20 ÷ 100 = 100 g.
  • One part: 100 ÷ (1 + 2 + 2) = 20 g, so mix 20 g starter + 40 g flour + 40 g water.
  • The 20 g of starter holds 10 g flour and 10 g water, so the levain holds 50 g flour and 50 g water: 100% hydration.

For the same 100 g of levain from a 100% starter:

Ratio Starter Flour Water
1:1:1 33.3 g 33.3 g 33.3 g
1:2:2 20 g 40 g 40 g
1:5:5 9.1 g 45.5 g 45.5 g

Starter or levain?

Both words are used loosely. Here a starter is the culture you keep going, and a levain is the portion you build from it for one bake. The feeding ratio calculator does the same split without the recipe step.

Timing

How long the levain takes to be ready depends on your starter and the temperature, so this page gives no time. Note how long yours took at a known temperature, then enter it in the schedule calculator, which scales it to the kitchen temperature of the day. The levain also adds flour and water to the dough. For the effect on hydration, use the hydration calculator.

Sources

  • Baker's percentage and feeding-ratio arithmetic (parts by weight). All numbers above are computed with it.