Sourdough Feeding Schedule Calculator

Introduction:

A sourdough feeding schedule has two jobs: build enough ripe starter for the bake and make that starter peak when the dough is ready to mix. The arithmetic is simple because starter, flour, and water are weighed in ratios. The timing is less exact because a starter is a living culture affected by temperature, flour type, hydration, feeding ratio, and how active the culture was before the feed.

Feeding ratios are written as mature starter : fresh flour : water. A 1:1:1 feed adds equal weights of seed starter, flour, and water and usually peaks sooner. A 1:5:5 build uses much less seed relative to fresh food, so it usually takes longer and can suit an overnight levain. Hydration changes the water part. At 100% hydration, flour and water weights match. At 65% hydration, the build is stiffer, peaks differently, and may hold shape longer.

Peak is a practical window, not a clock appointment. A ripe starter may be domed, bubbly, expanded, aromatic, and still able to lift dough. A starter that has collapsed may still flavor dough but can weaken rise. Warm kitchens, rye and whole-grain flour, and very active starters shorten the window. Cool kitchens, high feeding ratios, sluggish cultures, and some stiff builds stretch it. The right schedule often comes from combining a calculated estimate with repeated notes from the same jar and kitchen.

There is also a stock-management side to feeding. A levain build can leave too little mature starter for the mother jar if the seed amount is not planned. A recipe target should include a small reserve for scale rounding, jar residue, and readiness checks. Discard or reserve decisions are easiest when the seed amount, usable starter amount, and leftover mother starter are calculated together before flour and water are mixed.

How to Use This Tool

1. Choose a feeding profile for overnight levain, same-day build, daily maintenance, fridge refresh, stiff levain, or a custom plan.
2. Select whether you want to work backward from a target ready time or project forward from a feeding time.
3. Enter usable starter needed, feeding ratio, hydration, kitchen temperature, flour type, starter activity, and mature starter available.
4. Use Advanced to add build reserve, mother starter to keep, early-use threshold, and ingredient display precision.
5. Review the feed time, peak time, usable window, ingredient weights, and guidance checks before mixing.

Interpreting Results

The summary shows the next important time. In target-ready mode, it reports when to feed. In feed-now mode, it reports the projected peak. The ingredient line gives the mature starter seed, fresh flour, and water weights, followed by the estimated time to peak.

The Feeding Plan Table is the time sequence: measure seed, feed the build, start checking at the early usable threshold, use near the peak target, and note the latest practical use. The Ingredient Weight Table is the scale workflow. The guidance rows flag seed shortfall, timing problems, warm or cool kitchens, flour activity, hydration texture, and whether the ratio is fast or slow. The Peak Timeline Chart is an estimate of rise over time, not a substitute for jar marks and visual cues.

Technical Details

The mass calculation starts from the amount of usable ripe starter you want at the end. A reserve is added first. The total build is then split into seed, flour, and water according to the selected ratio and hydration. Because the ratio is by weight, the same formula works for small maintenance feeds and larger levain builds.

Formula Core

S is mature starter seed, T is usable starter target, r is reserve as a decimal, F is fresh flour parts per 1 part seed, and H is hydration as a decimal. Fresh flour equals S x F. Water equals S x F x H. For 220 g usable starter, 6% reserve, 1:5 flour parts, and 100% hydration, total build is 233.2 g, seed is about 21.2 g, flour is 106 g, and water is 106 g.

Limitations and Accuracy Notes

Starter timing is an estimate. Flour freshness, water chemistry, jar shape, starter maturity, inoculation history, and room temperature swings can move the real peak earlier or later. Use the schedule to plan the feed, then trust visible cues from the starter before mixing dough. If the feed time has already passed, feed now and either warm the starter, lower the feeding ratio, or adjust the bake schedule.

Worked Example

A baker needs 180 g of ripe starter for a same-day mix and wants a 5% reserve. With a 1:2 flour ratio at 100% hydration, total build is 189 g. The ratio has 1 seed part, 2 flour parts, and 2 water parts, so seed is 37.8 g, flour is 75.6 g, and water is 75.6 g. If the kitchen is warm and the starter is strong, the peak estimate may land several hours sooner than the same feed in a cool kitchen.

FAQ

Is 1:1:1 always the right maintenance ratio?

No. It is common and fast, but higher ratios can reduce discard, slow the peak, and better match overnight or warm-room schedules.

Why does flour type affect timing?

Whole-grain and rye flours often provide more minerals and fermentable material, so many starters move faster with those feeds.

Should the starter be used exactly at peak?

Peak is a useful target, but the usable window depends on the starter and bread formula. A small window around peak is usually more realistic than a single minute.

References

• King Arthur Baking, Sourdough Starter Maintenance
• Sourdoughstarter.com, Starter Feeding Calculator Notes