Levain Build Calculator
A levain is an offshoot of your starter built for one particular bake: a small amount of starter fed a bigger meal, so it peaks right when your dough needs it and your main starter stays untouched.
Tell the calculator how much levain the recipe calls for (or its baker's percentage), choose a build ratio and a small buffer for what sticks to the jar, and it gives you the grams to mix.
Mix this
- Starter
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- Flour
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- Water
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- Total
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Runs entirely in your browser. Nothing you type is sent anywhere.
How to use it
- 1
Enter the levain weight from your recipe, or switch modes and enter the recipe's flour weight and levain percentage.
- 2
Choose a build ratio. Lower ratios like 1:1:1 or 1:2:2 peak sooner; higher ratios like 1:5:5 or 1:10:10 are ideal for builds that ferment overnight.
- 3
Add a buffer so scraping the jar doesn't leave you short. 10% is plenty.
- 4
If your starter isn't kept at 100% hydration, enter its hydration to get an accurate levain hydration.
- 5
Mix, cover, and use the levain at or just before its peak.
The math, explained
Levain from a percentage: levain = recipe flour × levain % ÷ 100. A recipe with 1,000 g of flour and 20% levain needs 200 g.
Add the buffer: build total = levain × (1 + buffer % ÷ 100). 200 g with a 10% buffer is 220 g.
Split by the ratio parts: starter = build total × starter parts ÷ (starter + flour + water parts), and likewise for flour and water. 220 g at 1:2:2 is 44 g starter, 88 g flour and 88 g water.
Levain hydration counts the starter's own flour and water: (water + starter water) ÷ (flour + starter flour) × 100, where starter flour = starter ÷ (1 + starter hydration ÷ 100). With a 100% starter and equal flour and water, the levain is 100% too.
The peak hint uses the same rule of thumb as the feeding calculator, at 24 °C (75 °F). Grams are rounded to whole numbers (to 0.1 g below 10 g), so totals can differ from the target by a gram.
Frequently asked questions
What's the difference between a starter and a levain?
They're the same culture. The starter is the jar you maintain long-term; a levain is a portion built from it for a specific bake, often with a different flour or ratio. Building a levain means you never use up or over-ferment your main starter.
How much levain should I use in sourdough bread?
Most sourdough bread recipes use 10–25% levain relative to flour. Around 20% gives a bulk fermentation of roughly 4–6 hours in a warm kitchen; lower percentages ferment more slowly and suit overnight or cool-kitchen schedules.
Can I use my levain before it peaks?
A levain that has risen well and is still climbing works fine and gives a milder flavour. Well past its peak it's more acidic and has less leavening power, so aim for the peak or just before rather than long after.
Why add a buffer to a levain build?
Some levain always stays behind on the jar, the spoon and the scale. A 5–10% buffer makes sure you still have the full amount your recipe needs. Leftover levain can go back into your starter jar or into your discard.
More sourdough calculators
- Sourdough Hydration Calculator Find your dough's true hydration with the starter's flour and water counted in, plus baker's percentages and a reverse mode for target hydration.
- Sourdough Starter Feeding Calculator Grams of starter, flour and water for any feeding ratio, plus an estimated time to peak at your kitchen temperature.
- Bulk Fermentation Calculator Estimate how long bulk fermentation will take from your dough temperature and starter percentage, and how much rise to aim for.
- Baker's Percentage Recipe Scaler Convert any bread recipe to baker's percentages and scale it to more loaves, a target dough weight or a simple multiplier.
Keep reading
- Cold Proof Sourdough: How Long, What Temperature and Why
How long to cold proof sourdough in the fridge, the best fridge temperature, when to start the cold retard, and how to bake straight from the fridge.
- How to Tell When Your Sourdough Starter Is Ready to Bake
Doubling, a domed top, bubbles, smell and timing: how to spot your starter's peak, why the float test misleads, and how temperature changes everything.
- Sourdough Starter Feeding Schedule: Counter, Fridge & 9-to-5
Counter vs fridge schedules, 1:1:1 vs 1:5:5 vs 1:10:10 ratios and how they move the peak, plus sample plans for a 9-to-5 week and vacations.