Why Do Muffins Sink in the Middle? Causes and Fixes

Too Much Leavening: The Primary Culprit

This is the most common reason muffins sink, and it is counterintuitive. You would think more baking powder equals more rise, and in a way it does — the muffin rises dramatically in the first few minutes of baking. But the structure of the muffin — the network of flour proteins, egg proteins, and starch that solidifies around the gas bubbles — needs time to set. If the gas production overwhelms the structure before it firms up, the muffin inflates like a balloon, then collapses when the gas escapes through the too-thin walls of the bubbles.

Think of it like blowing up a balloon too fast. A slow, steady inflation produces a solid, stable shape. Rapid over-inflation stretches the material thin and it pops — or in the case of a muffin, deflates.

The correct amount of baking powder for most muffin recipes is 1 to 1.5 teaspoons per cup of flour. Baking soda, which is about three to four times as potent as baking powder, should be used at about one-quarter teaspoon per cup of flour. If your recipe calls for more than these amounts and your muffins are sinking, try reducing the leavener by 25 percent and see if the results improve.

Also check that your baking powder is not double-acting in a recipe written for single-acting, or vice versa. Double-acting baking powder releases gas in two phases — once when mixed with liquid and again when heated — which means the total gas production is higher. Most modern baking powder is double-acting, but older recipes may have been developed with single-acting powder.

Over-Mixing the Batter

Muffin batter should be mixed until the dry ingredients are just incorporated — no more. The batter should look lumpy, with visible streaks of flour. This feels wrong to people who cook precise recipes or who were taught to mix things thoroughly, but in muffin baking, lumpy batter is correct batter.

Over-mixing develops gluten, the protein network in flour that gives bread its chewy texture. In bread, gluten is desirable. In muffins, it is not. Excessive gluten makes the muffin tough and creates a structure that is initially rigid enough to hold a tall rise, but then contracts as it cools. The contraction pulls the center of the muffin inward, creating the characteristic sunken dome.

The mixing technique for muffins is what bakers call the "muffin method." Whisk the dry ingredients together in one bowl. Whisk the wet ingredients together in another bowl. Pour the wet into the dry and stir with a spatula — not a whisk, not an electric mixer — using broad, gentle folds. Stop when you can no longer see large patches of dry flour. Twelve to fifteen strokes is usually enough. Small lumps are fine and expected.

This technique is the opposite of what works for bread-based recipes like sourdough, where extensive mixing and kneading develop gluten intentionally. Baked goods have different structural needs, and the mixing approach must match.

Oven Temperature Problems

Muffins need a blast of high heat at the beginning of baking to set the outer structure quickly, followed by steady moderate heat to cook through the center. When the oven temperature is too low, the outside of the muffin does not set fast enough. The leavener generates gas, the muffin rises, but the structure has not firmed, and when the gas eventually escapes or cools, the muffin deflates.

When the oven is too hot, the outside crusts over before the inside has finished rising. The center continues to expand under the crust, then collapses when it cannot hold the pressure after the oven door opens or the muffin cools.

An oven thermometer (available for a few dollars at any kitchen supply store) is the most reliable way to verify your oven's actual temperature. As with cookies that spread too flat, an oven that runs 25 degrees off from the set temperature makes a meaningful difference in the outcome.

Many experienced bakers use a two-temperature method for muffins: start at 425 degrees Fahrenheit for the first 5 minutes (this creates the initial rise and sets the dome), then reduce to 350 degrees for the remaining baking time (this cooks the interior gently without burning the top). This technique produces tall, well-domed muffins that hold their shape.

Opening the Oven Door

Every time you open the oven door, the temperature drops by 25 to 50 degrees Fahrenheit instantly. During the critical first 15 minutes of baking, this temperature drop can collapse muffins that have risen but not set. The gas inside the muffin cools and contracts, and the still-soft batter cannot hold the expanded shape.

Do not open the oven door for at least the first 20 minutes of baking. If you need to check doneness, look through the oven window. If you must open the door, wait until you are confident the muffins are nearly done (set structure, golden tops), and open it as briefly as possible.

Other Contributing Factors

Too much liquid. Extra milk, oil, or eggs make the batter too wet, which weakens the structure. Measure wet ingredients as carefully as dry ones. A tablespoon of extra milk does not seem like much, but in a 12-muffin batch, that extra moisture is distributed across all of them and can tip the balance.

Undermixed batter (the opposite of over-mixing) can also cause sinking if there are pockets of unmixed leavener that react all at once in one area of the muffin. The lumps in muffin batter should be flour lumps, not clumps of baking powder.

Altitude. At elevations above 3,500 feet, the lower air pressure allows gas to expand more readily, making over-rising and sinking more likely. High-altitude baking generally requires reducing leavener, increasing flour, increasing oven temperature slightly, and reducing sugar.

Filling muffin cups too full. Muffin tins should be filled about two-thirds to three-quarters full. Overfilled cups rise above the pan edge, lose the structural support of the tin walls, and are more prone to collapse.

Related: Cookies Spread Too Thin When Baking · Sourdough Crust Hard but Inside Gummy · Baking Soda vs Baking Powder