LoafTime

Bulk fermentation calculator

How long your dough needs to rise, and how much rise to look for.
Dough temperature
°F
Push a thermometer into the dough — it is often a little warmer than the room.
Starter, as % of the flour
%
100 g of starter for 500 g of flour is 20%.
Bulk fermentation at 75°F
Every starter % at that temperature, in one chart
Bulk takes about
5 hours
4–7½ hours · shape at a 30–50% rise
The rise tells you when — not the clock.
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How it works

Bulk fermentation is the first rise, from mixing until you shape. It depends most on the dough’s temperature, then on how much starter you used.
Warm dough rises fast and should be shaped at a smaller rise; cool dough needs longer and can rise more. The rise matters more than the hours.

Questions

How long is bulk fermentation?

With 20% starter, about 4–7½ hours at 75°F (24°C), 5½–10½ hours at 70°F (21°C) and 2½–5 hours at 80°F (27°C). Less starter takes longer.

How much should the dough rise in bulk?

It depends on the dough’s temperature: about 30–50% at 75°F (24°C), and only 25–30% at 80°F (27°C), because warm dough keeps rising fast after shaping.

How do I measure the rise?

Put a small piece of the dough in a straight-sided jar and mark its level. When the jar shows the rise you want, the whole dough is there too.

Sources

Sourdough Bulk Fermentation Chart (70°–85°F)
Sourdough Archive
The Ultimate Sourdough Bulk Fermentation Guide
The Sourdough Journey
Checked September 30, 2026. The figures are the bakers’; the model and the words are ours. Watch the dough, not the clock.

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