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.
Starter & Levain Studio
Know your starter. Build your levain. Weigh a feed, plan your next bake, and learn your jar’s rhythm.
Free to use · No account needed · Saved in your browser
YOUR BAKING WORKBENCH
Start with what you need today.
A starter is the culture you keep and feed. A levain is a portion of that starter you build for a particular bake.
First time here? See the three-step guide
- Choose your taskFeed your jar or prepare levain for a recipe.
- Enter your weightsUse your scale. You can change any starting assumption.
- Follow your mixing planAmounts update as you type. Check the jar for readiness.
Give your starter a name, such as “Sunday Starter,” and save its usual flour and feeding ratio. You can calculate first and save a profile whenever you’re ready.
All tools & advanced modes
Your mixing amounts update as you type.
View my mixing amountsStarter profiles, plans and journal entries stay in this browser. Export a backup to move them to another device.
FROM BERRIES TO BREAD · ANCIENT GRAIN SERIES
Changed the grain? Read the jar differently.
Activity and gas retention are different. A lively starter may show less height with einkorn, spelt or rye. Look at bubbles, texture, aroma and its own rise-and-fall pattern; a float test alone cannot tell the whole story.
What changes with fresh-milled and ancient grains?
Whole-grain bran changes water absorption and how gas is held. Einkorn’s protein does not behave like modern bread wheat; rye develops a different, paste-like structure. In rye dough, acidity and amylase activity also matter to the crumb.
When changing flour, keep the feeding weights deliberate and record the new mix separately. A blend with hard red or hard white wheat can ease the transition. Flour contributes its own flavor as well as structure. Learn the new jar before relying on its old schedule.
Fresh-milled describes the milling, not a single grain. Record the grain, whether it is whole or sifted, and the proportions in “Flour or flour mix.” Choosing a category does not automatically change hydration or peak hours.
YOUR NEXT LESSON
Ancient Grain Sourdough Starter
Explore einkorn, spelt, rye and modern wheat, then check your understanding.
Watch Henry’s lesson (opens in a new tab)Take the module quiz (opens in a new tab)A sourdough calculator for your own starter
Use Starter & Levain Studio to weigh a daily feed or build the levain a recipe needs. Save a starter profile, compare actual peak observations at similar temperatures and feeding ratios, or expand the advanced settings for precise hydration, dough formulas and multi-stage builds. It is free to use, with no calculator account required. Profiles, plans and observations are saved locally in your browser.
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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