Why is my sourdough flat, and how to fix it

If your sourdough is flat, the dough almost always lost its structure before it hit the oven. The four common causes are over-proofing, weak shaping, underdeveloped gluten, and hydration that runs too high for your flour. Each one leaves the dough unable to hold its shape, so it spreads sideways instead of springing up. All of these are fixable.

Over-proofing is the usual culprit

A loaf that proofs too long runs out of gas and structure. The yeasts and bacteria break down the gluten, the dough goes slack, and it can no longer trap the carbon dioxide that gives oven spring. You score it, it sighs, and it bakes wide and pale.

Watch the dough, not the clock. A finished bulk ferment grows by roughly 50 to 75 percent, shows some bubbles at the edges of the container, and feels alive and jiggly. The poke test helps: press a floured finger in about 1 cm. If the dent springs back slowly and partly, it is ready. If it stays put and the dough feels loose, you have gone too far. Times in any recipe are estimates, so judge by feel and rise.

If your kitchen is warm, fermentation moves fast. At 26 C (79 F), bulk might take 4-6 hours; at 21 C (70 F), it can stretch past 8. Cool the dough or cut the time when it is hot.

Weak shaping leaves no tension

Shaping builds a taut skin that holds the loaf upright. Skip it, or do it loosely, and the dough has nothing to push against as it bakes.

• Pre-shape into a round, rest 20-30 minutes, then do a final shape.
• Drag the dough across an unfloured surface to build surface tension. You want a tight, smooth ball that holds its dome.
• Stitch or fold a batard so the seam is closed and the skin is tight.
• Proof seam-side up in a banneton so the smooth side bakes upward.

Underdeveloped gluten

If the gluten network never came together, the dough cannot trap gas no matter how well you shape it. This shows up as a sticky, tearing dough that will not pass the windowpane test.

Give it time and folds instead of hard kneading. After mixing, let it rest 30-60 minutes (an autolyse), then do three or four sets of stretch-and-folds spaced 30 minutes apart during the first part of bulk. A few percent of whole wheat or rye adds strength and flavor. If you suspect your flour is the issue, a higher-protein bread flour (around 12 to 13 percent) builds a stronger network than all-purpose.

Hydration too high for the flour

Wetter dough spreads more, and not every flour can carry it. A 75 percent hydration dough that works with strong bread flour can turn into a puddle with weaker flour.

If your loaves keep going flat, drop the water. Try 68-70 percent while you build your shaping and timing, then climb back up once those are solid. Our hydration calculator makes it easy to dial in a number. For more on how a healthy culture should behave before you mix, see feeding your starter.

Quick diagnosis

What you see	Likely cause	First fix
Slack, no spring, spreads fast	Over-proofed	Shorten bulk, watch the rise
Holds shape in bowl, flat after baking	Weak shaping	Add tension, use a banneton
Sticky, tears, no structure	Weak gluten	More folds, stronger flour
Wet and runny from the start	Too much water	Lower hydration to 68-70 percent

Change one thing per bake and write down what you did. That is the fastest way to find which cause is yours.