How Many Cake Mixes for a Half Sheet Cake

I’m certainly not opposed to box cake mixes as they’re so handy! But it can be challenging to know how many to buy. Well, it all comes down to the height of your cake pan. While a half-sheet pan that’s only one inch thick can handle one or two cake mixes, a thicker pan will need more.

Hey, there, cake bakers! I’m Michelle, and I’ve been baking cakes for the past ten years. There’s nothing quite like a delicious, moist, and crumbly cake. I have used plenty of cake mixes in my day, so I know exactly how much to buy. Spoiler alert: always buy more than you need.

If you’re stuck in the cake-baking aisle wondering how many boxes of cake mix to buy for your half-sheet cake, don’t panic! I’m here to help. Below, you will find just how many cake mixes are for a half-sheet cake and other useful information.

Let’s talk cakes!

How Many Boxes of Cake Mix Do you Need for a Half Sheet Cake?

There isn’t really a right or wrong answer for this. It all depends on the height of your cake pan and what kind of cake mix you’re buying. Let me explain further.

If you have a half-sheet cake pan (13×18), but it’s only an inch deep, you won’t need as much cake mix as something that has a cake pan that’s two, three, or four inches deep (or even deeper – wow!).

It also depends on the type of cake mix you’re using. Some may provide enough mix to fill a 9×13 cake, while others can handle more or less. So, always double-check what the packaging says. Then, you can decide how much you’re going to need.

The basic answer is between one and four cake mixes. This should be able to handle almost every kind of half-sheet cake pan successfully. However, I always suggest buying more than you need. The last thing you want is too little cake mix.

What to do when there’s not enough cake mix?

So you got home, only to realize you didn’t take my advice and bought too little cake mix for your half-sheet cake. Don’t worry – it’s not over yet. You should always have a “cake extender” mix on hand for times like these.

To make a cake extender, simply mix 1 ½ cups flour, 1 cup sugar, two teaspoons baking powder, and ¼ baking soda. Place it in an airtight container such as a mason jar. Then, when you need to extend your cake, add six tablespoons of the mixture and continue as usual. 

You might need to add a little bit more milk or water when using the extender. It all depends on how dry your batter is. 

What to do when there’s too much cake mix?

If you bought too much, don’t worry, either. In fact, be excited! There are so many ways you can use leftover cake mix.

  • Freeze it. If you want, you can simply place it in an airtight container or plastic bag and plop it into the freezer. Then, you will have some cake mix ready to go the next time you have a hankering for some cake.
  • Make waffles. Who said breakfast had to be healthy all the time? Cake waffles are not only delicious, but they’re a surefire way to make sure your kids eat their breakfast. Save it for a holiday like Thanksgiving or Christmas for a super special breakfast!
  • Make a milkshake. Cake batter milkshake? Yes, please! This indulgent dessert is exactly what you need to satisfy a sweet tooth. Blend it with anything you’d like, such as strawberry and strawberry milk, to make a fun pink strawberry cake milkshake.
  • Mini cupcakes! Mini cupcakes are some of my favorite things in the world, and they freeze well. Make a batch and take one out of the freezer each morning to stick in your lunchbox as a treat.

Try any one of these delicious recipes using leftover cake mix!


So, it’s pretty simple. Pay attention to the cake mix you’re buying and the height of your half sheet cake pan to decide how many you need. If you still have questions, though, let’s dive into these frequently asked questions to find an answer!

How many cake mixes do I need for a 12×18 pan?

Again, it all comes down to the type of cake mix and the depth of your pan. However, opting for three cake mixes will typically be enough. Remember – always buy more than you need. You can always freeze or repurpose any that’s left over.

Can you bake a cake in a half-sheet pan?

Yes, you can, but it will be pretty thin. You can always enjoy a thin mini cake, or you can bake multiple and stack them. I would recommend going with an actual half-sheet cake pan, though, for the best results.

Can you put 2 cake mixes in a 9×13 pan?

It’s unlikely that you will need two cake mixes for a 9×13 pan, but there is no harm in trying. As long as the batter doesn’t fill the pan to the top, then you won’t have a big mess or problem on your hand.

Does one box of cake mix make two cakes?

If you’re using small pans, such as six or seven inches, then you can likely use a single box of cake mix to make two cakes. I’d have two boxes of cake mixes on hand, though, just in case you need a little bit more.

Final Words

If you’re trying to create a half-sheet cake, you will likely need at least two boxes of cake mix. Depending on the depth of your pan, though, you might need up to four boxes. Pay attention to instructions on the cake mix, though, and calculate how many you need to fill up your pan.

Have you ever made a half sheet cake using cake mix boxes? How many boxes did you end up using? We would love to hear from you, so comment below!

About Michelle
I have been a lover of sweets since day one. This led me on a self-taught baking journey starting at the age of 13. It's been over 10 years since the start of my baking adventures, and I’ve learned a lot along the way. Now, people rave about my delectable treats, whether it’s a chocolate cake or a strawberry crepe.

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