You follow the recipe. You feed your starter. You wait patiently for that perfect bulk fermentation. And then you pull a flat, pancake-like disc out of the oven and wonder: what went wrong?
The frustrating part? There isn’t just one answer. A flat loaf can come from seven completely different causes — and the fix for one problem is useless if you’re actually dealing with a different one.
Here’s the good news: once you learn to read your dough, you can diagnose exactly which problem created your flat loaf and fix it on the next bake.
🍞 Free Download: Sourdough Troubleshooting Flowchart Can’t remember if flat loaves mean under-fermentation or over-fermentation? Download the free visual flowchart that shows you exactly which symptom points to which problem — and the one-step fix for each. Get the Free Flowchart →
The Quick Diagnosis: 4 Key Questions
SURGICAL ADD — Diagnosis Flowchart Logic: Before diving into all seven causes, ask yourself these four sequential questions. Your answers point you directly to the culprit:
1. Did your dough rise much during bulk fermentation?
NO → Go to #2
YES, it got bubbly and puffy → Go to #3
2. Did the dough collapse into soup when you shaped it?
YES → Over-fermentation (#2)
NO → Starter issue (#1) or under-fermentation (#3)
3. Did the shaped dough hold its form during proofing?
NO, it spread sideways → Weak shaping (#4) or hydration too high (#6)
YES, it held shape → Go to #4
4. Did the loaf spring in the oven or did it stay flat?
NO spring = flat → Steam issue (#5) or oven temperature (#7)
Small spring but still dense → Under-fermentation (#3)
This diagnostic tree narrows down seven possible causes to one or two in seconds. Use it every time you get a flat loaf — it removes the guesswork.
7 Reasons Your Sourdough Is Flat (And How to Fix Each One)
1. Your Starter Isn’t Strong Enough
This is the #1 cause of flat sourdough. A weak or immature starter simply can’t generate enough gas to leaven the dough properly.
Signs: Dough barely rises during bulk fermentation, even after 6+ hours. The crumb is dense and tight. It might even have a gummy texture.
Fix it:
Feed your starter at a 1:1:1 ratio (starter : flour : water by weight)
Wait until it doubles within 4–8 hours at room temperature (75°F / 24°C). This is peak activity
Use it exactly at peak — not before, not after. Use a rubber band to mark the starting level in your jar so you can see when it doubles
If your starter is under 2 weeks old, keep feeding daily. Most starters don’t become reliably leavening-capable until day 14+
For more on this, see Why Your Sourdough Starter Isn’t Doubling and How to Strengthen a Weak Sourdough Starter.
2. Over-Fermentation
The opposite problem: your dough fermented too long. When bulk fermentation goes past its peak, the dough loses gluten strength and collapses.
Signs: Dough rose beautifully during bulk, but when you shaped it, it was sticky, gassy, and basically turned to soup in your hands. The gluten structure broke down.
Fix it:
Shorten your bulk fermentation window. Instead of “until it doubles,” try “until it reaches 75% rise” — this catches dough at peak strength before it over-extends
Use the aliquot jar method to track fermentation progress objectively without disturbing the main dough
If your kitchen is warm (above 78°F / 26°C), bulk fermentation will move faster than recipes suggest. Check every 30 minutes once you see visible rise
Over-fermented dough is still edible — it just won’t rise in the oven. Slice it thin, toast it, and enjoy it as a vehicle for olive oil or soup
3. Under-Fermentation
Your dough didn’t ferment long enough. The yeast and bacteria didn’t have time to build gas or develop flavor, so your crumb stays dense and your loaf stays flat.
Signs: Dough has visible bubbles but didn’t rise as much as you expected. Baked loaf is dense and heavy, with small, irregular air pockets (or none at all).
Fix it:
Extend bulk fermentation. The target isn’t time — it’s a visual milestone. Use bulk fermentation cues: dough should look aerated, have rounded edges, and show visible bubbles throughout (not just on top)
If your kitchen is cold (below 70°F / 21°C), bulk fermentation will move slowly. This is fine — just give it more time. A cold kitchen might need 8–12 hours for full bulk fermentation instead of 4–5
Use the aliquot jar method to track when 50–75% rise is achieved — that’s your target, not a specific time
Add one more set of stretch and folds if dough looks weak after 3 hours — this builds additional gluten strength and allows more gas production
4. Weak or Poor Shaping
Even perfectly fermented dough will produce a flat loaf if shaping doesn’t create surface tension.
How shaping works: Shaping creates a tight, smooth outer surface that traps gas inside the dough. Without this surface tension, gas escapes and the dough spreads sideways instead of rising upward.
Signs: Dough holds shape for a moment after shaping, but spreads flat during proofing. It looks like a pancake going into the oven.
Fix it:
Preshaped dough should be pre-shaped, rested for 20-30 minutes, then shaped again with tension. This two-step process builds the tight exterior you need
During final shaping, pull the dough toward you with controlled tension — don’t just roll it. Imagine tightening the surface of a balloon without popping it
A wet counter makes tension impossible. Use a lightly floured counter for shaping
If you’re using a banneton (proofing basket), dust it well with rice flour so the shaped dough doesn’t stick and lose tension
Shaping technique takes practice. Your first 5–10 loaves might be imperfect, and that’s normal. Watch videos of professional bakers shaping — seeing the movement helps more than reading about it.
5. Inadequate Steam or Oven Spring Phase
SURGICAL ADD — The Oven Spring Race: Baking is a race between two processes happening simultaneously: oven spring (the dough’s final explosive rise) and crust formation (the hardening of the outer surface). Whichever process “wins” determines your final loaf shape.
Steam keeps the crust flexible during the first 20 minutes of baking, giving the loaf maximum time to rise before the outer surface hardens. Without steam, the crust sets immediately and the race is over before it started.
Signs: Loaf went into the oven with good shape but came out flat. It didn’t spring at all, or sprang very little. Crust is pale rather than deep brown.
Fix it:
Dutch oven method (most effective): Preheat your Dutch oven to 500°F (260°C) for at least 20–30 minutes. The cast iron retains heat and creates an intense steam chamber. Bake covered at 475°F (246°C) for 20 minutes, then uncovered at 425°F (218°C) for 20–25 minutes
SURGICAL ADD — Preheat Duration Matters: Most home bakers don’t preheat long enough. After your oven reaches temperature, the Dutch oven needs 15–20 additional minutes to fully heat through. This ensures the bottom of your loaf gets immediate, intense heat — the key to oven spring. Skipping this step is why loaves often don’t spring
Open bake method (less effective but doable): Use a preheated baking steel or pizza stone. Create steam by placing a shallow metal pan on the lower oven rack and pouring boiling water into it right as you load the bread. Bake at 475°F (246°C) for the first 20 minutes (steam phase), then 425°F (218°C) for 20–25 minutes (crust phase)
Do NOT open the oven door during the steam phase (first 20 minutes). Each time you open it, steam escapes and oven spring stops
For complete baking guidance, see How to Bake Sourdough in a Dutch Oven.
6. Hydration Too High for Your Skill Level
SURGICAL ADD — Hydration Threshold Concept: Hydration is a threshold variable, not a linear one. A 5% increase in hydration doesn’t produce a 5% increase in difficulty — it can shift your dough into an entirely different handling category.
Here’s why: dough hydration determines how much water the flour absorbs. Higher hydration means wetter dough, which is stickier, harder to shape, and needs stronger gluten development to hold gas. If your skill level doesn’t match your hydration, the dough spreads flat during proofing.
Hydration ranges by skill level:
Beginner (first 10–15 loaves): 68–70% — Dough is stiff enough to shape confidently, wet enough to develop decent gluten through stretch-and-folds. This range is forgiving of timing mistakes
Intermediate (3–6 months experience): 70–76% — Sweet spot for most home bakers. Produces open crumb, good oven spring, but still manageable to shape. Most successful sourdough loaves live here
Advanced (1+ year experience): 76–82% — Produces Instagram-worthy open crumb with large irregular holes. But requires strong gluten development, confident shaping, and good fermentation judgment. A beginner at this hydration will get flat loaves 90% of the time
Expert only (2+ years): 82%+ — Very slack, sticky dough. Requires bannetons to contain the dough. Only attempt after mastering 76–80% consistently
SURGICAL ADD — True Hydration Calculation: Most bakers calculate hydration wrong, not knowing that starter water and flour count too.
If your recipe says “75% hydration” and uses a 100% hydration starter (equal weight water and flour), you’re secretly getting higher actual hydration because of the starter’s water content.
True hydration = (All water including starter water) ÷ (All flour including starter flour) × 100
Example: 500g flour + 100g starter (50g flour, 50g water) + 325g water = true hydration of (325+50) ÷ (500+50) = 72%, not 65%.
If your dough feels wetter than the recipe says, check your true hydration. You’re probably higher than you think.
Fix it:
Drop hydration by 3–5% on your next bake
Master your current hydration level for 10+ consecutive loaves before increasing
Use the true hydration calculator (search “sourdough hydration calculator” with your starter’s actual hydration percentage)
For deep hydration guidance, see Sourdough Hydration Explained.
7. Oven Temperature Is Wrong
Most home ovens are inaccurate by 25–50°F. If your oven runs cool, the loaf won’t get the intense initial heat needed for oven spring.
Signs: Loaf baked pale instead of deep brown. It barely sprang, even though fermentation looked good. Baking time needed to be much longer than the recipe said
Fix it:
Buy an oven thermometer ($8–15). Place it inside your oven and preheat normally. Check what temperature it actually reaches — compare to your oven’s display
If your oven runs cool, increase your set temperature by the difference. If it reads 450°F when you set it to 475°F, start setting it to 500°F
Bonus: Scoring Depth and Angle Matter
SURGICAL ADD — Scoring’s Role in Rise: Scoring (slashing the top of your loaf before baking) controls where the dough expands. A deep, angled score (30–45 degrees) creates a “flap” that flips open during oven spring, directing rise upward. A shallow or straight score provides less directional control.
Weak scorelines won’t hurt, but deep confident slashes give your dough room to spring without tearing randomly across the crust. If your loaf is spreading flat sideways instead of rising up, a deeper score (¼ inch deep) angled at 45° helps redirect that energy upward.
Bonus: Parchment Paper Can Trap Heat
SURGICAL ADD — Parchment Paper Impact: Parchment paper affects bottom heat transfer. If you use a large piece of parchment that wraps around the sides of your loaf in the Dutch oven, it can reduce the internal baking temperature by as much as 30°F. This prevents full oven spring and leaves the crumb underbaked.
Fix: Trim parchment to just under the loaf (not the sides), or use a silicone sling instead. For the last 10 minutes of baking (uncovered phase), you can remove parchment entirely to let the bottom crust finish browning.
The Troubleshooting Decision Tree (One-Step Fix)
Use this tree FIRST before reading the sections above. It points you directly to the problem:
Symptom: Dough didn’t rise during bulk
→ Problem: Weak starter
→ Fix: Feed starter at 1:1:1 until it doubles within 4–8 hours. Use at peak only
Symptom: Dough was bubbly, then collapsed when shaped
→ Problem: Over-fermentation
→ Fix: Shorten bulk to 75% rise instead of full double. Use aliquot jar method
Symptom: Dough has bubbles but didn’t rise much during bulk
→ Problem: Under-fermentation
→ Fix: Extend bulk fermentation. Target visual cues, not time. Add extra stretch-and-folds
Symptom: Shaped well, but spread flat during proofing
→ Problem: Weak shaping OR hydration too high
→ Fix: Practice two-step shaping with tension. Or drop hydration 3–5%
Symptom: Held shape, entered oven, then didn’t spring
→ Problem: Steam/oven spring issue OR low oven temp
→ Fix: Use Dutch oven preheated 20–30 minutes. Check oven temp with thermometer
Print this decision tree and stick it on your fridge. It cuts troubleshooting time from hours of confusion to 30 seconds.
What To Do With Your Flat Loaf Right Now
First: it’s still edible and usually still tasty. Sourdough flavor develops during fermentation, not in the oven. Your flat loaf has the same tang and complexity as a tall one — just denser.
Toast it — Slice thin, toast until crispy, and use as a bread vehicle for olive oil, tapenade, or soup
Make croutons — Cube, toss with oil, bake at 375°F for 15 minutes until golden
Bread crumbs — Dry it out in a low oven, then pulse in a food processor
Panzanella — Cube, toss with tomatoes, basil, olive oil, and vinegar
Then: Learn from it. Write down what happened at each stage — fermentation time, dough feel, shaping difficulty, oven behavior. On your next bake, change one variable at a time and watch what happens.
Related Guides for Flat Loaf Prevention
Learning one of these topics will prevent most flat loaves:
Aliquot Method for Sourdough — Measure bulk fermentation objectively. This single technique fixes 50% of flat loaf problems
Bulk Fermentation vs. Proofing — Know the difference and when each ends
Sourdough Hydration Explained — Understand how 5% changes your dough completely
How to Bake Sourdough in a Dutch Oven — Master steam management for maximum oven spring
How to Strengthen a Weak Sourdough Starter — If starter strength is your issue, this rehab protocol works
Why Your Sourdough Starter Isn’t Doubling — Diagnose exactly what’s weak about your starter
🍞 Download the Sourdough Troubleshooting Flowchart Stop guessing about flat loaves. Get the free visual flowchart that walks you through the diagnosis in 30 seconds, with the one-step fix for each problem. Get Free Flowchart →
Still stuck? The best way forward is to pick ONE variable to change on your next bake. Don’t change shaping, hydration, fermentation time, AND oven temperature all at once — you won’t know which change fixed the problem. Master each variable sequentially. Your flat loaf is teaching you something; listen to it.