Sourdough Clock

Sourdough Bulk Fermentation Time at Different Temperatures

By Tam Vu · Updated

On this page
  1. How it works
  2. Example: a 5-hour bulk at 24 °C (about 75 °F)
  3. What the model does not know
  4. Source

There is no single correct bulk fermentation time. It depends on your starter, your flour and, above all, the temperature. What stays dependable is how time changes with temperature for the same dough. This page takes one bulk you already did and tells you how long the same dough would take at other temperatures.

Bulk fermentation at other temperatures

The 5 hours at 75 °F are an example, not a standard. Replace them with your own bake.

How it works

The calculator uses the growth model for the sourdough yeast Candida milleri from Gänzle, Ehmann and Hammes (1998). The model gives a relative growth rate γ for each temperature. A step takes longer when γ is smaller:

new time = your time × γ(your temperature) ÷ γ(new temperature)

The model works between 18 and 30 °C (64 to 86 °F), so the calculator stops outside that range. It does not model the fridge. Cold proofing in the refrigerator is outside the range, so enter that time yourself in the schedule calculator.

Example: a 5-hour bulk at 24 °C (about 75 °F)

Dough temperature Time compared with yours Bulk would take about
18 °C (64 °F) 2.26× 11 h 18 min
20 °C (68 °F) 1.63× 8 h 10 min
22 °C (72 °F) 1.24× 6 h 12 min
24 °C (75 °F) 1.00× 5 h
26 °C (79 °F) 0.88× 4 h 24 min
27 °C (81 °F) 0.86× 4 h 19 min
28 °C (82 °F) 0.88× 4 h 23 min
30 °C (86 °F) 1.07× 5 h 20 min

The times stop falling after about 27 °C. In the model the yeast grows fastest near 27 °C and slows above it, so a hotter dough is not a faster one. The temperature guide explains why.

What the model does not know

It was fitted to cultures of one yeast and one bacterium strain, not to your starter, so it gives relative speeds, not the finishing point. Time is only one signal: watch the dough itself, and use your own earlier bakes as the reference. To hit a dough temperature, work out the water temperature with the desired dough temperature calculator.

Source