Sourdough Bulk Fermentation Chart: Temperature, Rise, and Signs

Sourdough bulk fermentation is complete when the dough has accumulated the rise, aeration, and strength expected by its formula—not merely when a timer rings. Track average dough temperature, measure the rise from a marked start, and confirm bubbles, elasticity, and surface shape before preshaping.

Define the phase before timing it

Bulk fermentation is the first fermentation of the whole dough mass. For a typical naturally leavened bread, begin the bulk clock when the starter or levain is incorporated—not after the last fold. The phase ends when the dough is divided or preshaped. Shaping and final proof come afterward.

That definition matters because recipes place folds at different points. Starting the clock after folding can silently erase hours of fermentation; treating final proof as part of bulk makes comparisons between formulas meaningless. Washington State University’s sourdough process material likewise separates the first rise or bulk fermentation from the second rise after shaping.

Write down four moments: inoculation, each fold, end of bulk, and shaping. This small log makes it possible to diagnose whether a dense loaf needed more bulk, more final proof, or simply gentler handling.

Sourdough bulk fermentation chart: temperature and rise targets

Yeasts and lactic acid bacteria produce gas and acids as fermentation proceeds. Within a bread recipe’s intended range, warmer dough generally moves faster and cooler dough more slowly. Measure dough temperature soon after mixing and again during bulk, then use the average as a planning input. Room temperature is only a proxy: the dough can begin warmer because of the water, mixing friction, or a warm starter.

University of Illinois Extension publishes the following rise targets in its Sourdough 101 method. They are useful examples of how one formula compensates for temperature before a refrigerated proof; they are not universal targets for every flour, inoculation, hydration, or schedule.

The warmer dough is stopped at a smaller rise because it carries more fermentation momentum into shaping and chilling. Copying “double in volume” from the coolest row into an 80°F dough would change the method. Conversely, copying 30% into a cool, low-inoculation dough may end bulk prematurely. Start with the tested targets in your chosen recipe and use your observations to execute that recipe—not to invent a universal temperature chart.

Measure rise in a container you can read

Place the dough in a straight-sided transparent container after mixing. Smooth the top without degassing it, mark the starting level, and cover the container. If the container has volume markings, record the starting volume. A rise from 1.0 liter to 1.5 liters is 50%; a rise from 1.2 liters to 1.8 liters is also 50%.

A sloped bowl distorts height, so a one-centimeter increase near the bottom does not represent the same volume as one centimeter near the top. An aliquot jar—a small sample tracked beside the dough—can help, but it introduces its own errors if the sample temperature, handling, or container differs. Use it as one measurement, not as permission to ignore the main dough.

Folds redistribute gas and can temporarily lower the visible height. Mark the initial level and evaluate the settled dough after the scheduled folds. Do not repeatedly press the dough flat to obtain a neat measurement; that changes the structure you are trying to judge.

Use a multi-signal end-of-bulk check

Measured rise is the anchor, but several supporting observations protect against a bad mark or an unsuitable container. Before ending bulk, check all of the following against the expectations of your formula:

• Temperature: Is the dough running warmer or cooler than the recipe assumes?
• Rise: Has it reached the recipe-specific increase from its marked start?
• Aeration: Are bubbles visible at the sides and under the surface?
• Shape: Does the surface look smoother and slightly domed rather than dense and flat?
• Movement: Does the dough feel lively and jiggle as one aerated mass?
• Strength: After the planned folds, can it hold together without being tight and undeveloped?

No single bubble or jiggle proves doneness. The value lies in agreement: a marked rise plus widespread aeration and appropriate strength is stronger evidence than elapsed time alone. The finger-poke test is not a good bulk test. It was developed as a final-proof cue, and dough strength or recent folds can make its response misleading during bulk.

A worked decision example

Imagine a recipe expects 50% rise around 75°F before preshaping and a cold final proof. You mix at 76°F, record 74°F two hours later, and mark 1.4 liters in a straight-sided tub. The average of those two temperature readings is about 75°F. When the dough reaches 2.1 liters, it has risen 50% because the gain of 0.7 liter is half the 1.4-liter start.

Do not end bulk from the arithmetic alone. Confirm that the surface is aerated, bubbles are visible at the edges, and the dough holds a smoother, livelier mass. If the volume mark says 50% but the dough appears dense, first check whether the starting mark was taken before the dough settled or whether a sloped container created a false reading. If the signals agree, proceed to preshape even if an internet timetable predicts another hour.

Hydration changes handling and visible structure. Use the sourdough hydration calculator to count the flour and water contributed by the starter; then compare this bake only with formulas of similar composition. Hydration does not generate an automatic bulk time.

Adjust the next bake without chasing the clock

If bulk consistently finishes too early

Use cooler mixing water, reduce the inoculation only if the formula allows, or mix later. Do not change temperature, starter amount, and hydration at the same time. Confirm first that the starter was used at a comparable stage in each test.

If bulk is far slower than expected

Verify dough temperature and starter readiness before extending indefinitely. A cold dough or weak starter explains more than the wall clock. Keep the dough in a food-safe environment and follow the formula’s process boundaries; do not use improvised high heat to force activity.

If the dough spreads at preshape

Spreading can reflect excessive fermentation, insufficient gluten development, high hydration, weak flour, or rough handling. Review the temperature and measured rise along with fold quality. One symptom cannot identify the cause.

Connect bulk to the final proof

Fermentation does not stop at preshape. Dough continues to change during the bench rest, shaping, and final proof, and it cools gradually in a refrigerator. Ending bulk is therefore a handoff decision. A warm, highly aerated dough may need a smaller bulk rise before a long cold proof; a cooler dough headed for a short room-temperature proof may follow a different target.

Record the baked result. A tight crumb alone does not prove under-bulk, and a flat loaf alone does not prove over-bulk. Combine crumb, loaf profile, dough feel at shaping, final-proof behavior, and the bulk log. Then make one measured adjustment on the next bake. The final-proof guide provides a separate decision framework for the shaped loaf.

Food-safety boundaries

Do not taste raw dough to assess fermentation. The FDA and CDC warn that raw flour can contain harmful microorganisms; thorough baking is the kill step. Wash hands, utensils, and work surfaces after raw-flour contact. This guide explains fermentation cues, not a validated control for pathogen reduction.