A levain is a sourdough preferment — a small portion of ripe starter mixed with fresh flour and water and allowed to ferment to peak activity before being added to a final dough. The levain is usually 15-25% of the recipe's total flour weight.

How do I build a levain from my fridge starter?

Take ~10g of your refrigerator starter. Add flour and water to reach the levain weight needed for your recipe. Let it ferment at 76°F until peak (typically 4-8 hours). Use at peak for maximum leavening power.

Levain Build Calculator

A levain is a preferment — built from a small portion of ripe starter and allowed to reach peak activity before mixing into the final dough. Use the main calculator below to set levain percentage and hydration; the recipe output shows the levain weight you need to build.

Total flour(g)

Target hydration(%)

Salt(%)

Levain of flour(%)

Levain hydration(%)

Flour to add: 450 g
Water to add: 325 g
Salt: 10 g
Levain @ 100%: 100 g
Total dough: 885 g
Effective hydration: 75%

How the math works

Total water = flour × hydration %. Your levain contributes 50 g flour + 50 g water — both count toward the totals. You add only the remainder as fresh flour and water.

Salt % is computed on total flour weight, not final-dough flour.

Open 75% hydration guide →

Levain size vs fermentation speed

10-15% levain: slower fermentation (5-6h bulk at 76°F), milder flavor.
15-20% levain: typical artisan target (4-5h bulk at 76°F), balanced flavor.
20-25% levain: faster fermentation (3-4h bulk at 76°F), more pronounced sour.
25-35% levain: enriched doughs (panettone, brioche) where fat slows yeast.

The gear that makes the math work

A short, honest baking kit. The scale matters most — every weight on this page is in grams. The Dutch oven is what turns a good crumb into a great crust.

Digital kitchen scale (0.1 g)
Baker's percentage is by weight, not volume — a 0.1 g scale is what makes the math on this page accurate.
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Dutch oven / combo cooker
Traps steam for the first bake phase — the single biggest factor in oven spring and a blistered, glossy crust.
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Banneton proofing basket
Wicks moisture and holds shape during the final proof, so high-hydration dough doesn't spread flat.
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Bread lame + bench scraper
A sharp lame scores clean ears; a steel bench scraper handles wet, sticky dough without tearing the gluten.
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High-protein bread flour
The math assumes ~12–14% protein. Real bread flour absorbs the hydration you calculate — all-purpose won't.
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Danish dough whisk
Mixes shaggy, high-hydration dough in seconds without the gluey mess of a spoon or your hands.
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🎧 Or learn the craft by ear

The numbers here are the what; a good baking book is the why. An Audible trial gets you any title free — Michael Pollan’s Cooked(the “Air” chapter is the best story ever told about why bread rises) is a perfect first listen.

Start a free Audible trial →

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Gear guides — what actually matters