Common Reasons Why Cakes Sink

It happens to the best of us: you spend all this time mixing up cake batter and feeling extra optimistic about those future cake layers, come to find that when you open the oven door your cakes have sunk. Before you blame the recipe, there are many things that can factor into the chemistry of your sunken cake creation. Baking is a series of chemical reactions, which can be cool and frustrating all in the same day!

After my fair share of sunken cake layers, I took to researching why exactly a cake recipe (even one you’ve had success with in the past!) would deflate in the center. Without further ado, here are the top 9 reasons I could gather: 

1: Your Baking Powder is Expired

Baking powder is one of the ingredients that gives your cake a beautiful rise. Unlike baking soda, which pretty much lasts forever, baking powder will expire between 6 months and one year. It’s especially sensitive to humidity and moisture, so to preserve it for as long as possible, you need to ensure it’s well stored in a cool, dry pantry.   

I always write the date that I open a new can of baking powder on the lid just to remember how long I have until it expires. If you’re not sure how long it’s been, you can test your baking powder by adding ½ teaspoon into a cup and adding ¼ cup of boiling water. If it bubbles up immediately, it’s still good. If not, it’s important that you get a new tin before baking a cake recipe. Sadly, expired baking powder won’t allow for the chemical reaction that a cake needs to rise. 

2: Too Much Leavening Agent 

If there’s too much baking powder or baking soda in a cake recipe, it can cause your cake to rise too rapidly, then sink shortly thereafter. The amount really depends on the other ingredients of the recipe.

A general rule of thumb for the amount of leavening agent in a cake recipe is one teaspoon of baking powder and/or ¼ teaspoon of baking soda per cup of flour. There are exceptions to this for sure, as not all cake recipes have both leavening agents. Some cake recipes that are ultra acidic (like a lemon cake) will require less baking powder to rise because the acidity of lemons cancels it out. See? So much science. 

3: Over-Creaming the Butter and Sugar 

The process of creaming the butter and sugar in a cake recipe is super important to the rise (or fall) of the cake. The majority of gas bubbles are created in the creaming process, and those are responsible for creating both texture and rise. A good rule of thumb is to cream the butter and sugar at a moderate speed for 2-3 minutes. Any more than that and you can end up either losing those precious gas bubbles or creating so many that the cake will rise too quickly and then sink immediately thereafter. 

I tested this theory with my vanilla cake recipe and creamed the mixture for a little bit longer (four minutes) and it’s true – any more than 2-3 minutes, or any higher power on your mixer than medium, will whip too much air into the mixture and cause your cake to fall in the oven. Be sure to follow the recipe exactly when it comes to creaming the butter and sugar, and if you’re ever curious about the time it takes for this to occur (because sometimes recipes don’t specify a time), just cream the room temperature butter with the sugar for 2-3 minutes on medium and you should be good to go. It should be “light and fluffy” after that amount of time, which looks like this: 

4: Your Butter is Too Soft 

Baking involves quite a bit of patience, and bringing the butter to room temperature is no exception. But what exactly is “room temperature”? According to the internet, perfectly room temperature butter will be 68ºF, which means it’ll be a little soft when you press into it, but not so soft that it’s easy to indent with your finger or on the verge of melting. 

If your environment is especially hot, you need to keep an eye on your butter and make sure you don’t leave it out too long before starting on the cake batter. And on the flipside, attempting to soften your butter in the microwave often results in too-soft butter. Regardless of how you ended up with butter that is over-softened, creaming it with the sugar will result in air bubbles that are frothy, hence destroying your chances of a light and fluffy rise. 

5: Over-Beating the Batter 

The process of mixing up cake batter requires beating in just the right amount of air. The air that you beat in is partly responsible for the rise in your cake, and if you beat in too much, your cake will rise too rapidly in the oven and then sink. Over-beating will also overdevelop the gluten in the batter, which will make the texture of your cake more dense. This common problem typically happens at the end of a cake recipe, when you’re adding in the final dry and wet ingredients. 

At the end of most of my cake recipes, I have the mixer on low and add all of the dry ingredients at once and wait until they just start to come together before adding all of the liquid at once. I specify to wait no more than fifteen seconds after adding the liquid, and this is specifically to make sure the batter doesn’t get overmixed. Each cake recipe will require a different process, but just know that the longer you mix the final batter, the more problematic air you’re whipping into it.  

6: Your Oven is Too Hot 

Have you ever checked your internal oven temperature? Sometimes your oven display will read one temperature, while the actual temperature is different. If an oven is too hot, it can cause the cake to rise too rapidly and thus, sink in the remainder of the baking process.

Typically, the resulting cake will have over-baked edges and will be runny in the middle. If you’re ever concerned about your oven temperature, you can purchase a thermometer to place inside your oven to ensure that it’s the right temp. 

7: Opening the Oven Door Prematurely 

I know it can be tempting to want to see what’s going on inside of the oven, but if you open the door during the baking process it lets too much air escape, even if it’s just for a second.

So as to not disturb the oven environment, you can just flip on the oven light to see your cake through the glass and be sure to only open the oven door after the specified baking time to check for doneness. 

8: Your Ingredients Aren’t Room Temperature

It’s ultra important that all of your ingredients are room temperature before you mix up your batter.

This means that your eggs, butter, and all other dairy and liquids need to be room temperature, not any colder or warmer unless the recipe specifies otherwise.

9: It’s Just an Unreliable Recipe 

There are TONS of cake recipes on the internet, and surprise, not all of them are written properly or go through extensive testing. Some common reasons why cakes sink are too much liquid in the recipe, an incorrect amount of leavening agent, or other ingredients with off measurements. Recipe writing requires lots of testing, and I thoroughly test all of my recipes before publishing them for the world to see, but not all bloggers have the time (or ambition) for that. 

Finding the right cake recipe for you means trying out a few to see which ones you love. As long as you follow the detailed instructions and spend a little time comparing, I’m sure you’ll end up with a cake you love! 

Although it’s frustrating to end up with a sunken cake, remember that you might be able to salvage it by leveling off the cake layers. And if all else fails, you can always stress eat your cake layers (like I’ve done many a time), turn them into cake balls, or just dust yourself off and try again!

Want more Cake Basics? Head here to see all of the posts and learn the methods of caking I’ve come to love over the years. I’m cheering you on every step of the way!