Levain Builds: Timing the Relay
A levain build is a pit stop for your starter: a measured portion is fed fresh flour and water hours before mixing, so the dough meets a culture at its energetic peak instead of whatever state the maintenance jar happens to be in. It is the difference between "whenever the starter is ready" and a baking schedule that starts when you decide it does. The levain build calculator does the weights for each leg; the hydration guide covers the dough those weights end up in.
Why build at all
A maintenance starter lives between peaks - sometimes hungry, sometimes spent. Dough mixed with a spent culture gets a slow, unpredictable start, and mixed with a young one a sharp, acidic one. A build lets you choose the culture's age exactly: refreshed and held warm, it arrives at mixing time doubled and domed, with the mild, lactic character that makes open crumbs and clean flavor. It also keeps the maintenance jar on its own weekly rhythm, untouched by baking-day demands.
Sizing the build
The formula names the share: a dough at 20% levain built on 500 g of flour carries 100 g of levain in the mix. Build a little more than the dough needs - say 120 g - so the jar never gets scraped. The build's own feeding ratio matters too: a 1:1:1 build (starter : flour : water) runs fast and mild, while a stiffer or colder build trades speed for acidity and hold time. The calculator outputs the three weights for whichever ratio and target you choose.
Counting backwards from the bake
Scheduling a build is subtraction, not fortune-telling. A warm 1:1:1 build peaks about 4-6 hours after feeding; a cooler night runs it longer. Want to mix dough at 8 am? The build goes together at midnight or, at cooler room temperature, around dinner. The pricing rule is the same one that governs the bulk: cooler slows everything, at the dough level captured by the rising time calculator and, in winter kitchens, by the winter fermentation guide. The read that never fails: the build is ready when it has doubled, domed and smells lightly sweet - past that, it flattens and turns sharp.
Questions
Can I just use my starter instead of building a levain?
Yes - plenty of good bread is baked on starter straight from the jar. A build buys you a culture at its exact peak, at the size the dough needs, with a flavor profile you control (a cooler, longer build tastes more acidic; a warm one more lactic and mild). It also leaves your maintenance starter untouched and on its own schedule.
How much levain should I build?
Whatever the formula asks plus a spoonful of insurance. If the recipe calls for 20% levain in a dough built on 500 g of flour, that is 100 g in the dough - build around 120 g so nothing is scraped from the jar. The build calculator turns the target percentage and your feeding ratio into exact weights for each leg.
How do I time the build to my baking schedule?
Count backwards. A levain fed at 1:1:1 and held warm peaks roughly 4-6 hours after feeding; a cooler or firmer build runs longer. If the dough gets mixed at 8 in the morning, a warm build goes together at night. The same temperature math that prices the dough bulk - the rising time calculator and the winter guide cover it - prices the build too.