Guide
Feeding Your Starter: Ratios and Peak Timing
A starter that peaks at 2 a.m. is a scheduling error, not a personality trait. The same clock that runs bulk runs the jar. Feeding ratio decides how much food each cell gets. Temperature decides how fast they eat it.
The calculator's mix card builds a 1:2:2 levain (seed : flour : water) sized to the mix, and assumes it's at peak when you mix. That 1:2:2 at 24°C is five hours — the same five-hour reference as a 20% bulk. Miss the peak and you didn't "use a young starter." You moved the bulk window.
Read it as: 1:n:n means 1 part ripe starter, n parts flour, n parts water, at 100% hydration. A 1:1:1 is a short fuse. A 1:5:5 is an overnight build. Peak looks like this: doubled (or a little more), domed on top, webbed inside — just before it falls.
When will it peak?
Hours to peak — same timing as bulk. Warmer jar goes faster, more food per starter goes slower:
Time to peak
t(T, n) = 5.0h · 2((24 − T) / 8.5) · (n / 2)
Reference: 5.0 hours at 24°C with a 1:2:2 feeding. n is the flour (and water) parts. Double the food per seed and you double the wait. Drop 8.5°C and you double it again.
The table: temp vs. feeding ratio
Hours from feed to peak at 100% hydration. Gold cell is the 5.0 h 1:2:2 reference. Read down for more food per seed, right for a warmer jar.
| Jar °C | 1:1:1 | 1:2:2 | 1:3:3 | 1:5:5 | 1:10:10 |
|---|---|---|---|---|---|
| 18° | 4h 5m | 8h 9m | 12h 14m | 20h 23m | 40h 47m |
| 20° | 3h 28m | 6h 56m | 10h 24m | 17h 19m | 34h 39m |
| 22° | 2h 57m | 5h 53m | 8h 50m | 14h 43m | 29h 26m |
| 24° | 2h 30m | 5h | 7h 30m | 12h 30m | 25h |
| 26° | 2h 7m | 4h 15m | 6h 22m | 10h 37m | 21h 14m |
| 28° | 1h 48m | 3h 37m | 5h 25m | 9h 1m | 18h 3m |
| 30° | 1h 32m | 3h 4m | 4h 36m | 7h 40m | 15h 20m |
A 1:1:1 at 24°C is 2h 30m — useful before a late mix, useless if you feed at bedtime. A 1:5:5 at 22°C is about 14h 30m: feed at 8 p.m., mix at 10:30 a.m. A 1:10:10 at 18°C is a 32-hour culture, not a levain.
Building exactly what you need
You need a weight, not a guess. Size the jar to the mix, then pick the ratio that peaks at mix time. For a 1:n:n build at 100% hydration:
To build W grams
- seed = W / (1 + 2n)
- flour = n · W / (1 + 2n)
- water = n · W / (1 + 2n)
Total parts = 1 + 2n. In plain English: divide your target weight by the total parts, then multiply by each part. The calculator's mix card is n = 2 (1:2:2): starter is one-fifth of the levain you weigh into the dough.
100 g · 1:2:2 · 24°C
- Seed 20 g
- Flour 40 g
- Water 40 g
- Peak ~5h
Calculator default. Feed five hours before mix in a 24°C room.
150 g · 1:5:5 · 22°C
- Seed 13.6 g
- Flour 68 g
- Water 68 g
- Peak ~14h 43m
Overnight build. Less seed, more food, same 150 g at mix.
Peak, then bulk
Mix at peak and the bulk fermentation guide is honest. Mix before the peak and the calculator stretches bulk by 1.22×. Mix after it has fallen and bulk compresses by 0.88× — acid already spent part of the window in the jar.
Do not “just add more starter” to cover a collapsed jar. That changes the starter amount and bulk together. Rebuild, or own the late-starter factor on purpose.