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Why build a levain at all
Plenty of sourdough recipes list “levain” rather than “starter”, and the difference is mostly about control. A levain is a one-off build made from a spoonful of your starter, sized for a single bake. You choose its hydration, its flour and how fast it ripens, and your main jar stays untouched in the fridge.
This builder is for bakers following recipes from books and bakeries, where the levain has a set weight and hydration. You enter what the recipe asks for, and it tells you how much ripe starter, fresh flour and water to combine so the finished levain hits that target exactly, including the flour and water hiding inside the starter you carry over.
How to set it up
- Type the amount from your recipe into Levain in the recipe.
- Use Extra for jar and spatula to cover what never makes it into the bowl. Around 10 g is usually enough.
- Set Levain hydration to the figure the recipe gives. If it says nothing, 100% is the usual assumption.
- Pick a build ratio under Starter : fresh flour. 1:1 or 1:2 ripens in a few hours; 1:5 or 1:10 is slower and suits an overnight build. Custom lets you type Fresh flour per part of starter yourself.
- If you want some whole grain in the mix, enter its share in Whole grain or rye flour. It is a percentage of the fresh flour only.
- Under Your starter, fill in Seed starter hydration and Room temperature.
Worked example: an overnight rye-speckled levain
A recipe wants 200 g of levain at 100% hydration. You add 10 g for the jar, plan an overnight build at 1:5, want 20% of the fresh flour to be rye, and your seed starter is also kept at 100%. Overnight, your kitchen hovers around 21 °C. The builder gives:
- Ripe starter: 19 g
- White flour: 76 g
- Whole grain or rye: 19 g
- Water: 95 g
- Levain built: 210 g
- Flour inside the levain: 105 g
- Water inside the levain: 105 g
- Time to peak (guide): about 10 h to 15 h
At equal hydrations the maths collapses into parts again: 1 + 5 + 5 = 11 parts, and 210 ÷ 11 is about 19 g per part. The fresh flour is five parts, around 95 g, split 80/20 into 76 g of white and 19 g of rye.
The interesting case is a stiff levain. Change Levain hydration to 60% and keep everything else. The builder now asks for 24 g of starter, 95 g of white flour, 24 g of rye and only 67 g of water. The finished levain holds 131 g of flour and 79 g of water, which is 60%. The seed starter brought water of its own, so the builder trims the fresh water to compensate.
The peak estimate is only a guide. It scales with the build ratio and with temperature, but real starters differ in strength, and a whole grain portion tends to bring the peak forward.
Tips and pitfalls
- Match the levain’s flour to the recipe. A few grams of rye noticeably speeds up the build and adds a darker, earthier flavour.
- Stiff levains often taste tangier. Many bakers find that a firm, cool levain leans toward acetic sharpness, while a wet, warm one tastes milder and more yoghurt-like.
- Don’t reuse the recipe’s hydration for your starter. The two are separate numbers, and the builder keeps them separate for good reason.
- If the builder reports that the hydration cannot be reached, your seed starter already carries more water than the target allows at that ratio. Raise the hydration or use more fresh flour per part of starter.
Need to top up your main jar at the same time? The starter feeding calculator does that. If you are designing a whole loaf rather than following a recipe, start with the sourdough recipe builder, then come back here to build the starter it asks for.
Levain questions
Is a levain different from a starter?
Biologically they are the same culture. The word levain usually means a portion built specifically for one dough, often with its own hydration and flour, while the starter is the ongoing culture you keep and feed.
Why does the builder ask for my seed starter’s hydration?
Because the seed carries flour and water into the build. When the seed and levain hydrations differ, the fresh water has to be adjusted so the finished levain lands on the target. At 1:10 the effect is tiny; at 1:1 it matters.
My levain peaked far earlier than the estimate. What happened?
Warmth, whole grain flour and a very active starter all shorten the build. The estimate follows a standard temperature curve, so treat it as a starting point and note how your own starter behaves for next time.
How long can a ripe levain wait before I mix?
An hour or so past peak is usually fine. If you need longer, move it to the fridge to slow it down, or start the next build with a larger ratio.