Levain Build Calculator
Sourdough recipes often call for more levain than you keep on hand. Enter what you have, what the recipe needs and your feed ratio to see how many build stages get you there, with exact flour and water for every stage.
Results
- Stage 1
- 20 g starter + 40 g flour + 40 g water = 100 g
- Stage 2
- 100 g starter + 200 g flour + 200 g water = 500 g
The last stage lands slightly above the target because each stage multiplies the whole batch by the same factor - keep the surplus for maintenance feeding.
How staged builds multiply
Each stage feeds the entire previous result, so the amount multiplies by (1 + flour parts + water parts) every time: a 1:2:2 build grows the culture fivefold per stage. Working out how many stages bridge the gap between your starter and the recipe's levain tells you when to start - and gives you the flour and water to weigh at each step.
For everyday maintenance feeds that do not chase a recipe target, the starter feeding calculator covers both directions, and the rising time estimator shows how temperature moves the peak you are timing each stage against.
Frequently asked questions
Why does the last stage overshoot my target?
Every stage feeds the whole batch and multiplies it by the same factor, so the final amount lands on the next multiple of that factor: 20 g at 1:2:2 gives 100 g, then 500 g, even if the recipe only asked for 400 g. The surplus keeps in the fridge for maintenance feeding or a second loaf.
What ratio should I use for a build?
1:1:1 triples the culture each stage but acidifies fastest; 1:5:5 grows it elevenfold per stage and dilutes acidity more, which is why recipes wanting a mild levain often call for one generous 1:5:5 build instead of several small ones. Both reach the same final amount - the trade-off is time per stage versus number of stages.
How do I know when a stage is ready for the next feeding?
Watch for peak rather than the clock: the mass has visibly expanded, looks domed and bubbly, and smells yeasty-sweet rather than sharply acidic. At 21-24 C that is usually 4-6 hours after feeding. Feeding a collapsed, over-acidic stage weakens the culture and the final rise with it.