Why Do Cupcakes Sink After Baking?
Sunken centers are one of the most common cupcake problems. The good news: they’re almost always fixable once you know the cause.
A cupcake rises when gas from leavening and trapped air expands in the oven. The structure sets when proteins and starch coagulate. If the center never gets hot enough to set, or if the structure is too weak to hold the rise, the middle collapses as the cake cools.
| Cause | Fix |
|---|---|
| Underbaking | Bake until skewer comes out clean; use thermometer ~98–99°C in centre |
| Overmixing | Mix wet and dry just until combined; stop as soon as flour is in |
| Too much leavener | Measure correctly (no heaping); use fresh BP/BS |
| Overfilling liners | Fill 2/3 full; use a scoop for even portions |
| Opening oven early | Don’t open until last third of bake; rotate only then if needed |
| Expired leavener | Test BP in hot water (should fizz); replace every 6–12 months |
Underbaking is the number-one cause
If the centre never reaches a high enough temperature, the starch and proteins there never fully set. The outer ring is set but the middle stays soft; as it cools, that soft centre can’t support the dome and it sinks.
Recipes give times as guidelines. Your oven and pan size affect the real bake time. Rely on doneness cues, not the clock alone.
- Skewer or thin knife in the centre: no wet batter (a few moist crumbs are fine).
- Instant-read thermometer in centre: ~98–99°C (208–210°F) when done.
- Preheat 15–20 minutes; use middle rack; don’t crowd the pan.
- If oven runs cool: add 5–10 min or raise temp slightly; note the time for next batch.
Overmixing weakens structure
When you mix flour with liquid, gluten forms. A little gives structure; too much makes the batter tough and weakens the crumb’s ability to hold gas. Overmixing also pushes out air you beat into the butter and eggs.
The result: denser batter that may rise in the oven but doesn’t have a strong enough network as it cools, so the centre collapses.
- Mix wet and dry only until no dry pockets remain; stop as soon as flour is incorporated.
- A few small lumps are better than a smooth, overmixed batter.
- Wet in one bowl, dry (sifted/whisked) in another; add dry in 1–2 additions; fold or low speed.
- Stand mixer: lowest setting for the final step; mix only until combined.
Too much leavener or expired leavener
Baking powder and soda produce gas. Too much and the batter can rise very fast then collapse before the structure sets. The bubbles get too big and the crumb can’t support them.
Expired leavener may not produce enough gas, so the centre doesn’t set properly and can sink.
- Measure with a proper spoon (or scale); don’t heap. Check you’re not using tablespoon for teaspoon.
- Test baking powder: 1 tsp in hot water — should fizz. No reaction = replace.
- Test baking soda: drop of vinegar — should bubble.
- Store in a cool, dry place; replace every 6–12 months.
Overfilling the liners
More than about two-thirds full and the extra batter in the centre takes longer to bake. The top and sides set while the middle is still wet; when it cools, it can sink.
- Portion so each liner is about two-thirds full.
- Use a scoop for even portions and a modest dome.
Opening the oven too early
Opening the door in the first half or two-thirds of the bake lets cold air in and can drop the temperature. The rising batter is still fragile; a sudden drop in heat can make it fall before the structure sets.
- Don’t open until cupcakes look set and are close to done.
- If you rotate for even browning, do it in the last third of the bake and close the door quickly.
Other factors: sugar, liquid and altitude
Recipes with a lot of sugar or liquid set more slowly and have softer structure; they can be more prone to sinking. Bake a bit longer or at a slightly higher temperature so the centre sets.
At high altitude, batters can rise more and then collapse. Follow altitude-adjusted instructions (often less leavener, more liquid, higher oven temp) and rely on skewer and thermometer for doneness.
Prevention checklist
- Preheat the oven fully and use an oven thermometer to verify the temperature.
- Fill liners two-thirds full; use a scoop for even portions.
- Mix wet and dry just until combined; avoid overmixing after adding flour.
- Use fresh baking powder and baking soda; test them if you’re unsure.
- Don’t open the oven until the last third of the bake; then only briefly if needed.
- Test doneness with a skewer (no wet batter) and optionally a thermometer (~98–99°C in the centre).
Pro tip
Bake one test cupcake first if you’re using a new recipe or oven. Note the time and appearance when the centre is done; then use that for the full batch.
More troubleshooting
For a full list of common cupcake problems and fixes, see our 10 cupcake mistakes and how to fix them. For practice with controlled mixing and baking, try Classic Vanilla Dream or Red Velvet Romance.
Summary
- Why they sink: Centre doesn’t set (underbaking); structure too weak (overmixing or too much leavener); dome too heavy for core (overfilling); or opening oven too soon / expired leavener.
- Fix: Bake until skewer is clean; fill liners two-thirds full; mix just until combined; use fresh leavener.