How to Tell When Bulk Fermentation Is Done (Without Guessing)

The most common failure point in sourdough is bulk fermentation — either ending too early (dense crumb) or going too long (overproofed, flat, sticky). Here's how to read the dough.

The five signs of properly bulked dough

1. Volume increase of 50–70%

Use a straight-sided container with markings. The dough should rise visibly — not double, but well past its starting point. Less than 30% rise: under-fermented. More than 100%: likely over.

2. Domed, smooth surface

A properly fermented dough develops a slight dome on top, not a flat or sunken surface. The surface should look smooth, almost glossy.

3. Visible bubbles on the surface and sides

You should see bubbles through the side of the container — a few large ones near the top and many small ones throughout. If you see no bubbles at all, it's not done.

4. Jiggle test

Gently shake the container. The dough should jiggle like a soft pudding, not slosh like batter and not sit stiffly.

5. Pulls cleanly from the container

When you go to turn out the dough for shaping, it should release in one piece, leaving a slightly stretchy webbing behind. If it's gluey and won't release, it's overproofed. If it tears stiffly, it's under.

The three signs of overproofed dough

1. Surface is bubbly but starting to deflate

Lots of bubbles, but the dome has flattened or sunken in the center.

2. Smells strongly alcoholic or sharply sour

Some sour smell is normal. A strong vinegar or alcohol smell means fermentation has gone too far.

3. Won't hold a shape

When you try to shape it, the dough spreads back out within seconds. It has no structure left.

Why timers fail

Recipes give time ranges (4–6 hours) but ignore your kitchen. A 75°F kitchen ferments much faster than a 68°F kitchen. The same dough that takes 4 hours in summer takes 6+ hours in winter.

Use the dough, not the clock.

A simple visual check method

Pinch off a 30g piece of your dough at the start of bulk and put it in a small straight-sided cup or jar. Mark the starting line. When that piece has risen 50%, your bulk dough is also done.

This trick works because the small sample ferments at the same rate as the bulk dough but is easier to see.

Temperature matters more than time

If your dough temperature is:

• 70°F → bulk takes 6–8 hours
• 75°F → bulk takes 4–5 hours
• 80°F → bulk takes 3 hours
• 85°F → bulk takes 2 hours

Use a probe thermometer to check dough temperature halfway through bulk. Once you've baked a few loaves at known temperatures, you'll learn your kitchen's rhythm.

What "ready" looks like in three different kitchens

A cold winter kitchen might give you bulk dough that's 50% risen, slightly cool to the touch, and smells faintly sweet. A summer kitchen might give you dough that's 70% risen, warm to the touch, and smells more tangy. Both can be done — context matters.

The most reliable rule

Underproofed bread is dense but recoverable (you'll still eat it). Overproofed bread is flat, gummy, and not as enjoyable. When in doubt, end bulk slightly early. The cold retard during the final proof will continue developing the dough.