Sourdough Starter Peak Time Estimator
Estimate when a mature sourdough starter may peak from its feeding ratio, ambient temperature and feeding time, then check the visual cues that matter more than the clock.
Estimated peak window
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Estimated peak window
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Treat the clock as a starting point. The visual cues below are more reliable.
| Temp | 1:1:1 | 1:2:2 | 1:5:5 |
|---|
Trust the starter, not just the clock
At peak, look for these signs
- Roughly doubled or tripled in volume.
- A domed top just beginning to flatten.
- Bubbles throughout, with a tangy, yeasty smell rather than a sharply acidic one.
- A collapsed dome means it is past peak. Use a rubber band or straight-sided sample container to measure rise.
Whole grain and rye usually ferment noticeably faster than white. Young or recently revived starters are slower and less predictable; this model assumes a mature starter.
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How to read a sourdough starter peak chart
This sourdough starter peak chart uses the Q10 rule: fermentation rate roughly doubles for each 10°C increase. It also scales with the flour and water parts in the feeding ratio, because a smaller inoculation takes longer to consume its food.
The honest reference anchor is a 1:1:1 feed at 25°C (77°F) with a mature starter, which typically peaks in about 4–6 hours. The model uses 5 hours as the midpoint, so a 1:5:5 feed at the same temperature lands around 10–12 hours and a 1:1:1 feed at 21°C (70°F) around 7–8 hours. Treat every result as a window, not a promise.
Whole grain and rye flours ferment noticeably faster than white, while young or recently revived starters are slower and less predictable. Because no flour-specific rate is supplied here, flour type is shown as context rather than used to invent a multiplier.
estimated hours = 5 × 2^((25 − temperature °C) ÷ 10) × (flour parts + water parts) ÷ 2 Below about 15°C (59°F), the culture slows unpredictably; above about 32°C (90°F), bacteria can outpace yeast and change the result qualitatively. The visual cues are more reliable than the clock.
Sourdough starter peak time FAQ
What does peak mean?
Peak is when the starter has roughly doubled or tripled, has a domed top just beginning to flatten, is full of bubbles throughout and smells tangy and yeasty. Once the dome collapses, it is past peak.
Why is the result a window?
Starter strength, flour, temperature stability and feeding conditions vary. The clock gives a useful range, but the starter's rise, dome and bubbles should decide when it is ready.
Does flour type change the estimate?
Yes. Whole grain and rye generally ferment noticeably faster than white flour. This tool does not apply an invented flour multiplier, so use the visual cues and shorten your expectation when appropriate.
How can I measure rise accurately?
Put a rubber band around the jar at the feeding level, or place a small sample in a straight-sided container. Both make rise easier to compare than judging by eye.
What if my starter is young or recently revived?
Expect it to be slower and less predictable than this model. The estimate assumes a mature starter.