Count what’s in the seed.
Your starter already contains flour and water. We count both, so a 60% target means a 60% finished levain—even if your seed starts at 100%.
A little precision. A better bake.
Know your starter.
Build your levain.
The right amount, the right hydration, and a plan that fits your kitchen. From a small mother jar to a full bake day.
STARTER & LEVAIN STUDIO
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Tomorrow’s bake matters.
Separate the starter you keep in the original jar from the finished levain you reserve. Handling allowance is extra weight, not a promise of zero waste.
Observe before you predict.
Schedule from your own peak observations at comparable ratios, hydration, flour, and temperature. Until then, enter a planning assumption and watch the jar.
How the math works & sources
Feeding ratios are starter : fresh flour : fresh water, by weight. Hydration is water divided by flour, multiplied by 100. Equal flour and water means 100% hydration.
Your starter contributes flour and water. Starter flour = starter weight / (1 + hydration / 100); starter water is the remaining weight. We subtract both from the finished target to calculate fresh additions. Ingredients must balance to the target weight; impossible negative additions are blocked.
Build seed % uses fresh flour as its denominator. Dough prefermented flour % uses total recipe flour, including levain flour. Whole levain weight % uses that same total flour denominator, but counts the entire levain. These percentages are different. Starter kept in the original jar, extra ripe levain and handling allowance are separate amounts.
Calculations assume a flour-and-water starter with known hydration. Calculations use unrounded weights; displayed ingredients are rounded individually. Fermentation may change mass. Multi-stage builds carry the entire previous stage forward. Timing is a reminder to inspect your jar, not a promise of ripeness: temperature, flour, feeding ratio and your culture affect its behavior.
Sources: King Arthur Baking: baker's percentages and feeding ratios and their timing limits.
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