Sourdough Feeding Schedule Calculator

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Feeding profile:

Start from an overnight build, same-day build, daily maintenance, fridge refresh, or stiff levain.

Schedule from:

Choose the time you already know.

Desired peak time:

The schedule works backward to the estimated feeding time.

Planned feeding time:

The schedule projects the usable window forward from this time.

Ripe starter needed:

This is the amount available for use; an optional reserve can be added in Advanced.

40 g{{ formatWeight(target_starter_g) }}1,200 g

Feeding ratio:

Higher fresh-flour ratios usually need less seed and take longer to peak.

Fresh flour parts:

For a 1:4:4 feed at 100% hydration, enter 4.

1 : flour

Starter hydration:

Use a lower value for a stiff levain and 100% for a common liquid starter.

60%{{ formatNumber(hydration_percent, 0) }}%125%

% water

Kitchen temperature:

Temperature is an estimate input, not a substitute for checking the culture.

14 C{{ formatNumber(kitchen_temp_c, 1) }} C31 C

Feed flour:

Choose the flour blend used in this feeding.

Culture activity:

Recently refrigerated cultures usually need a slower profile than reliably strong starters.

Mature starter available:

A seed shortfall appears in the results when the current jar cannot supply the build.

Build reserve:

Use a measured allowance only when coming up short would disrupt the mix.

% extra

Mother starter to keep:

Use this only when the current jar must retain a specific amount for its next feeding.

Scale precision:

Choose the smallest increment your scale can reliably resolve.

Projected sourdough feeding and usable-window schedule
Step	Local time	Amount or marker	Bench cue	Copy
{{ row.step }}	{{ row.time }}	{{ row.amount }}	{{ row.cue }}

Exact and scale-rounded sourdough feeding weights
Ingredient	Ratio part	Exact	Weigh out	Preparation note	Copy
{{ row.ingredient }}	{{ row.part }}	{{ row.exact }}	{{ row.weighOut }}	{{ row.note }}

Seed, timing, temperature, and culture checks for the feeding plan
Check	Signal	Bench action	Copy
{{ row.check }}	{{ row.signal }}	{{ row.action }}

A sourdough starter does not peak on a fixed clock. Its rise reflects the amount of ripe culture carried into the feed, the fresh flour and water added, the room temperature, the flour blend, and the culture's recent activity. Ingredient weights can be exact while the peak time remains an estimate that must be checked against the jar.

Feeding ratios are written as seed starter to fresh flour to water by weight. A 1:1:1 feed contains equal weights of all three. A 1:5:5 feed uses much less seed relative to fresh food, so a given final build needs less mature starter and usually takes longer to peak. Hydration is the water weight as a percentage of fresh flour weight; it changes the third part of the ratio.

Higher fresh-flour ratios generally lengthen the build and reduce the seed required.
Warmer conditions generally shorten the rise, while a recently refrigerated or sluggish culture takes longer.
Whole-grain or rye flour can make a feed move faster than a comparable white-flour build.
Stiff and liquid starters show peak differently, so volume alone is not a universal readiness test.

Scheduling can run in either direction. If the mixing time is fixed, work backward from the desired peak to find a feeding time. If the feed is happening now, project the likely peak and usable window forward. Civil times are treated as the local wall-clock values entered, without converting between time zones.

A rounded dome, visible aeration, a repeatable rise, aroma, and the first signs of flattening or collapse provide stronger evidence than the projected minute. A weak culture may need one or more refreshes before it can follow a normal schedule, and food-safety decisions should never rest on a rise estimate alone.

How to Use This Tool:

Choose the time you know first, then describe the build and the culture as they actually are today.

Select a Feeding profile or start with a custom plan. Choose Desired peak time to work backward or Planned feeding time to project forward.
Enter the ripe starter needed and choose the feeding ratio. For a custom ratio, enter fresh flour parts; water parts follow from the hydration percentage.
Set hydration, kitchen temperature, feed flour, and culture activity. Use the temperature where the jar will sit, not a daytime room maximum.
Enter mature starter available, optional reserve, and any mother starter you want left after taking the seed. Choose the scale precision used for the displayed weigh-out.
Check the seed availability and mother-jar signals before following the schedule. Mark the starting level and begin observing the culture before the projected early-use time.

Interpreting Results:

The ingredient weights are arithmetic outputs; the peak and usable window are heuristic outputs. Weigh the seed, flour, and water to the selected scale increment, but treat the schedule as a check-in plan rather than a deadline.

Seed shortfall means the mature starter available is smaller than the calculated seed. Refresh more starter or reduce the build before feeding.
Mother-jar shortfall means the requested carryover will not remain after the seed is removed.
The early-use point is a projected 80% rise point. Use near the culture's repeatable peak cue; refresh again if it has collapsed sharply or smells abnormal.

Technical Details:

The calculation separates mass balance from fermentation timing. Mass balance is deterministic for the entered ratio and reserve. Timing multiplies bounded factors for ratio, temperature, hydration, flour, and observed activity, then clamps the estimate to the supported 2-to-36-hour range.

Formula Core:

Let F be fresh-flour parts and H be hydration percent. Water parts and total ratio parts are:

W = F \times \frac{H}{100}, P = 1 + F + W

The reserve is added to the usable target before the total is divided into seed, flour, and water.

T = U \times (1 + \frac{R}{100}), S = \frac{T}{P}, Flour = S F, Water = S W

Arithmetic retains full precision. Only the displayed ingredient weigh-out rounds to 0.1 g, 1 g, or 5 g; the rounded values are not fed back into the timing or shortfall calculations.

Mechanism Core:

The base peak time grows with fresh-flour parts. Temperature uses a doubling-style adjustment around 23°C, hydration makes a smaller correction, and flour and culture activity apply fixed factors.

t_{peak} = clamp ((3.2 + 2.3 F^{0.72}) \times f_{temp} \times f_{hydration} \times f_{flour} \times f_{activity}, 2, 36)

Flour and culture activity timing factors
Input	Factor	Effect relative to steady white-flour planning
White bread or all-purpose flour	1.05	Slightly longer
Mostly white with 10–20% whole grain	0.92	Shorter
Whole wheat / rye / spelt blend	0.82 / 0.70 / 0.88	Shorter by the listed factor
Sluggish / steady culture	1.35 / 1.00	Longer / baseline
Strong / very strong culture	0.82 / 0.70	Shorter

The temperature factor is clamped from 0.42 to 2.4. The hydration factor is clamped from 0.86 to 1.18. The projected hold window is 1.25 + 0.28F hours, plus 0.7 hour below 80% hydration, then clamped from 1.5 to 5.5 hours. The early-use point is approximately 86.49% of the estimated peak time.

Accepted ranges are 5 to 5,000 g target starter, 0.2 to 30 fresh-flour parts, 45% to 150% hydration, 4°C to 40°C, 0% to 30% reserve, and 0 to 1,000 g mother-starter target.

Accuracy Notes:

Fermentation speed is not determined by ratio and temperature alone. Starter age, acidity, microbial balance, flour batch, water, container shape, feed history, and measurement error can move the real peak outside the projected window.

Calibrate future plans from the same culture, ratio, flour, hydration, temperature, and jar.
Use the culture's repeatable rise and dome behavior as the authority when it disagrees with the estimate.
The local date and time fields do not resolve time zones or daylight-saving transitions.

Worked Examples:

Overnight 1:5:5 levain

A 220 g target at 100% hydration and no reserve contains 11 total parts. The build uses 20 g mature starter, 100 g flour, and 100 g water, leaving 40 g from an available 60 g mother starter. At 22°C with a steady culture and a mostly white flour blend containing some whole grain, the timing model estimates a peak in about 10.1 hours, an early-use check near 8.7 hours, and a 2.65-hour hold window after peak.