Sourdough bulk fermentation calculator
Enter your dough temperature and how much starter is in the dough to see how long bulk fermentation will take, and when to start checking it.
22°C. Measure the dough after mixing. Room temperature works if you have no thermometer.
Share of the flour, for a 100% hydration starter. 20% is typical.
Bulk fermentation starts when the starter goes in.
Bulk fermentation
- Bulk fermentation6–7½ hours
- 6½h
- Start checkingLook for about 50% rise
- 2:45PM
- Likely done byGrown 50–75%, domed and bubbly
- 4:30PM
Every 5°F (3°C) warmer cuts the time by about a quarter; every 5°F cooler adds about a third.
An estimate for a healthy starter. Go by the dough, not the clock. To plan the whole bake, use the schedule calculator.
Bulk fermentation time by temperature
Hours from mixing in the starter to shaping, for dough made with a 100% hydration starter. Whole grain flour ferments a little faster; a sluggish starter, slower.
| Dough temperature | 5% starter | 10% starter | 20% starter | 30% starter |
|---|---|---|---|---|
| 64°F (18°C) | 14–18 h | 11½–15 h | 9–11½ h | 7½–10 h |
| 66°F (19°C) | 12½–16 h | 10½–13½ h | 8–10½ h | 7–9 h |
| 68°F (20°C) | 11½–14½ h | 9½–12 h | 7½–9½ h | 6–8 h |
| 70°F (21°C) | 10–13 h | 8½–10½ h | 6½–8½ h | 5½–7 h |
| 72°F (22°C) | 9–11½ h | 7½–9½ h | 6–7½ h | 5–6 h |
| 74°F (23°C) | 8–10 h | 6½–8½ h | 5–6½ h | 4½–5½ h |
| 76°F (24°C) | 7–9 h | 6–7½ h | 4½–6 h | 4–5 h |
| 78°F (26°C) | 6½–8 h | 5–6½ h | 4–5 h | 3½–4½ h |
| 80°F (27°C) | 5½–7 h | 4½–6 h | 3½–4½ h | 3–4 h |
| 82°F (28°C) | 5–6½ h | 4–5½ h | 3½–4 h | 3–3½ h |
| 84°F (29°C) | 4½–6 h | 3½–4½ h | 3–3½ h | 2½–3 h |
| 86°F (30°C) | 4–5 h | 3½–4 h | 2½–3½ h | 2–3 h |
How temperature changes the time
The yeast and bacteria in a starter work faster as the dough warms up. As a rule of thumb, every 5°F (about 3°C) cooler adds a third to the time, and every 5°F warmer takes off a quarter. That is why the same recipe can take 5 hours in July and 9 in January.
The amount of starter matters less than you might think: halving it adds roughly one doubling time of the starter, about 1½ hours at 75°F. Use less starter to stretch the bulk for an overnight rise, or more to speed up a cold kitchen.
Signs that bulk fermentation is done
- The dough has grown 50–75% (less for whole grain dough, which can collapse if pushed further).
- The top is domed and smooth, with a few large bubbles.
- You can see bubbles along the sides and bottom of a clear container.
- It jiggles like set jelly when you shake the bowl, and feels airy and light when you tip it out.
Controlling the temperature
- Mix with warm water, around 80–90°F (27–32°C), to start the dough at the right temperature in winter.
- Put the bowl in the oven with only the light on, or on top of the fridge, for a warm spot.
- In summer, use cold water and less starter so the dough doesn’t race ahead.
- Plan the whole bake around these times with the sourdough schedule calculator, and work out the recipe with the sourdough calculator.
Tools for reading your dough
Weighing in grams is what makes sourdough repeatable. Links go to Amazon search results, so you can pick any brand.
- Instant-read thermometer
Dough temperature sets the pace of bulk fermentation. Around 75–78 °F (24–26 °C) keeps the timings in most recipes on track.
- Straight-sided starter jar
A clear jar with straight sides and a rubber band around it shows at a glance when your starter has doubled.
- Digital kitchen scale
Every number on this site is in grams. Any scale that reads to 1 g, holds at least 5 kg and has a tare button will do.
Questions bakers ask
How long should bulk fermentation be for sourdough?
It depends mostly on temperature. With 20% starter, expect about 8¼ hours at 68°F (20°C), 5½ hours at 75°F (24°C) and 4¼ hours at 80°F (27°C). Less starter takes longer. The dough is ready when it has grown 50–75%, not after a set number of hours.
How do I know when bulk fermentation is done?
The dough has grown by half to three quarters, the top is domed, there are bubbles on the surface and along the sides of the container, and it jiggles when you shake the bowl. A small sample of dough in a straight-sided jar, with a band at the starting level, makes the rise easy to read.
Can bulk fermentation be too long?
Yes. Over-fermented dough turns slack and sticky, tears instead of stretching, smells sharply sour and won't hold its shape, so the loaf spreads flat. If you catch it, shape it gently and bake it in a loaf pan, or make it into focaccia.
Can I do bulk fermentation in the fridge?
Yes. A cold bulk slows fermentation to a crawl, so dough that would take 6 hours on the counter can take 12–24 hours or more in the fridge. Many bakers give the dough a head start of 1–3 hours at room temperature before chilling it.
What is the best temperature for bulk fermentation?
75–78°F (24–26°C) is the sweet spot for most loaves: fast enough to fit in a day, slow enough to build flavor and easy to control. Cooler dough takes longer and tastes more sour; dough above 82°F (28°C) can over-ferment quickly.
Why is my bulk fermentation taking so long?
Usually the dough is cold, the starter wasn't at its peak when you mixed, or there isn't much starter in the dough. Mix with warm water, put the bowl somewhere warm such as the oven with only the light on, and feed your starter so it peaks when you mix.