How to Make Half a Cake Mix

Whether you’re looking to bake a smaller cake in your toaster oven or just don’t want to deal with lots of tempting leftovers, making half a cake mix is a great option. From pan choices to dividing eggs and substitutions, we’ll walk you step-by-step through how to split a cake mix in half.

Need ideas to use up the remaining cake mix? Check out this recipe for Small Batch Cake Mix Cookies, these thick and chewy Small Batch Cake Mix Cookie Bars, or treat yourself to a pair of these teeny-tiny Cake Mix Mini Cakes For Two! 

While we’re big fans of from-scratch cookies, cupcakes, and muffins sometimes it’s nice to grab a boxed mix and throw together an easy treat.

The problem is that a standard (15.25 oz) cake mix can leave you with lots of leftover cake, especially if you’re cooking for just one or two people.

Dividing the mix seems like a great solution but it can lead to lots of questions. Like how do you divide an egg, what size pan should I use, does it need to bake for the same amount of time?

Below, we’ll answer all of those questions and more!

At over 1,500 words, this post ended up being a little longer than we expected (I blame all the egg attempts). So we put together a table of contents for you.

If you want to skip ahead, click on the part you’re interested in and you’ll be taken right to it.

Table of Contents

• Splitting The Mix in Half
• Divide The Water and Oil In Half
• Halving Eggs + Substitutions
• Choosing Your Pan
• Oven vs. Toaster Oven vs. Convection Temperature
• Mix and Bake

STEP 1: Divide The Cake Mix In Half

The ingredients in your boxed cake mix have been sitting and settling for a bit on that grocery store shelf. Before you get started, grab the bag and give it a quick shake to mix everything up.

Now, you could try to dump half the bag out but dividing the mix into equal portions will yield the best results. Here are two ways to go about it.

Option 1: Using a Scale

A standard boxed cake mix (in the US) weighs 15.25 ounces. So half a box of cake mix weighs 7.625 ounces.

To measure out half, place a medium bowl on your scale and zero it out. Pour the mix into the bowl until it measures 7.62 ounces.

Option 2: Using Measuring Cups

A cake mix that weighs 15.25 ounces has 3⅓ cups of mix total. So half a box of standard cake mix is 1⅔ cups.

To measure out half, use the spoon-and-sweep method. This method will keep you from compacting the mix and taking more than half.

1. Place a piece of parchment paper on your counter.
2. Spoon the mix into a dry measuring cup and use the back of a knife to level off the mix.
3. Repeat until you have 1⅔ cups of mix measured out.
4. If you have any of the dry mix on the parchment paper, pour it back into the bag with the other half of the cake mix.

Did that sound confusing? If it did, check out this post by Sugar Spun Run on How To Properly Measure Flour. 

Okay, now that you’ve got your mix divided let’s look at the other ingredients.

STEP 2: Divide The Water and Oil In Half

Take the amount of water called for and divided it in half. So, if the box instructions call for 1 cup of water use 1/2 cup.

When it comes to the oil, some boxed cake mixes (like Betty Crocker and Pillsbury) call for 1/2 cup of oil while others (like Duncan Hines) use 1/3 cup.

Take whatever the instructions on your box call for and divide it in half.

• Half of 1/2 cup = 1/4 cup or 4 tablespoons
• Half of 1/3 cup = 2 tablespoons + 2 teaspoons

I usually make our cake mix with olive oil or avocado oil but you can use any vegetable oil you want.

If you use coconut oil (in a liquid state), just make sure the other ingredients are at room temperature (and not cold). Otherwise, the coconut oil will harden into lumps and muck up your batter – it will be sad.

STEP 3: Halve The Eggs + Substitutions

If the box calls for 2 eggs, just use one egg.

But what if it calls for 3 eggs?

The Quick Answer: Use one whole egg + half a beaten egg.

To measure out the beaten egg, crack an egg into a small bowl and beat with a fork until the white and yolk are combined. Measure out half, about 1½ to 2 tablespoons (give or take a little). For more tips check out this How to Measure Half an Egg post.

*You’ll want to refrigerate the remaining beaten egg and use it within 24 hours.

The cake we made using this method turned out great. It was moist with a nice flavor and light texture. Just what you’d expect from a cake mix.

BUT…that leftover beaten egg was a little inconvenient and potentially wasteful. So we wanted to see if it could be avoided.

We grabbed more lemon cake mix, divided the boxes up and tried out some substitutions.

Applesauce

First, we replaced all of the eggs with 1/4 cup of unsweetened applesauce. (Spoiler: don’t do this – it’s not a great option).

The Results: The cake barely rose, was lacking in flavor and when I tried to cut it after cooling, it cracked and fell apart.

Would We Do It Again? Nope.

Greek Yogurt

Another option is to replace all of the eggs with 2 tablespoons of plain yogurt, regular or Greek variety.

The Results: The cake didn’t rise much but it did hold together well and tasted great. The crumb was denser but not in a bad way.

Would We Use This Substitution Again? Yep. I think the pound cake-style texture would be perfect for pairing with whipped cream and berries, especially for a summer brunch or Mother’s Day treat.

Egg + Greek Yogurt

The last option we tried was using one egg plus a tablespoon of yogurt.

The Results: This cake was tender, had a nice flavor and was lighter than the all-yogurt option. While it did crumble some, it didn’t fall apart like the applesauce one.

Would We Use This Substitution Again? 100% Yes! Overall it had a great flavor and nice texture. Plus it was so easy to grab a spoonful of yogurt and add it in with the 1 egg.

New! What about using 1 egg + part of another egg?

A lot of small-batch baking recipes call for a single egg white or a single egg yolk (like our rich and fudgy toaster oven chocolate cookies). Leaving you with some part of an egg to use up.

To see if an extra egg yolk or an egg white would make a good addition to half a cake mix we grabbed a box of the same lemon cake mix from before and got baking.

The first option we tried was one large egg plus an egg yolk.

The Results: While the crumb was a little heavier it was still very tender and moist. Because of the added yolk, the cake had a deeper yellow color and the extra fat did cause it to brown faster around the edges and on top.

Would We Use This Substitution Again? Absolutely! The cake’s lemon flavor really came through. It was a little denser than a traditional cake mix but not in a bad way.

The second option we tried was one large egg plus an egg white.

The Results: At first, I was a little concerned because the cake had a faint eggy smell while it was cooling. But once the cake had cooled completely and we cut into it all I could taste/smell was a nice lemon flavor. The texture was very light and bouncy.

Would We Use This Substitution Again? Definitely, the cake tasted delicious and we both really enjoyed the lighter texture.

About a week after this marathon baking session we decided to try two more options. Making half a mix using only 1 egg and using 2 eggs.

The 1-Egg Results: The cake was noticeably drier than the other cakes. While it still had some structure it crumbled easily. When you took a bite, the cake would kind of fall apart in your mouth.

Would We Use This Substitution Again? Probably not. This cake was definitely better than the applesauce option, but it wasn’t something I enjoyed. Tim did say he would eat it again.

The 2-Eggs Results: This cake rose taller than any of the other cakes, was super bouncy, and almost sponge-like. I felt like I could easily carve and frost it without a lot of crumbs.

Would We Use This Substitution Again? Maybe. Tim really enjoyed this cake. I thought it was light with a nice flavor but that it could use more moisture. I might try it again, swapping the water for milk and adding a little yogurt.

If you’re not sure which egg-option is for you, it’s always a good bet to stick with 1 whole egg + half an egg.

Here are a few ideas to use up the leftover egg:

• These small-batch triple ginger cookies use 1 tablespoon of egg.
• Make a batch of chocolate chip pecan oatmeal cookies with 1½ tablespoons egg.
• Grab a frying pan, scramble the egg and add it to a sandwich or salad.

STEP 4: Pick Your Pan

An 8 x 8 x 2-inch pan or an 8 or 9-inch round pan are good options for making half a cake mix.

If you don’t have one of those pans we’ve got a bunch of ideas for you!

• 8 1/2 x 4 1/2 Loaf Pan 
• 2 Round 6 x 2-inch Cake Pans 
• 2 6-cup Muffin Pans or a 12-cup Muffin Pan 
• 11 x 7-inch Cake Pan 
• Quarter Sheet Pan
• 8.5 x 6.5-inch Casserole Pan 

*Pro Tip: Use a plastic knife to cut the cake, it won’t scratch your metal pan.

Once you’ve got your pan sorted, make sure to grease it so your cake doesn’t stick.

STEP 5: Preheat The Oven

If you’re baking with a conventional ‘big’ oven, follow the box directions for the correct temperature setting.

For a standard toaster oven, I find reducing the temperature by 25 degrees yields the best results.

When using the convection option on our countertop oven, I reduce the temperature by 50 degrees (making sure not to go below 300F). This helps to give the middle enough time to cook through without over-baking the edges.

*As all ovens are different, you may need to play around a bit to find the perfect temperature setting for your specific oven.

STEP 6: Mix and Bake

Now that you’ve got your mix and ingredients divided, your pan selected and prepped, and your oven preheating all that’s left to do is mix up the batter and bake it.

Follow the directions on your package for combining half of the mix and half of the ingredients. Then pour the batter into your prepared pan and bake according to the directions.

Check On Your Cake Early

The type of mix, pan, ingredients, and oven used will affect the baking time.

• Cupcakes might take the same amount of time (ours took 15 minutes)
• Because it’s thinner, a quarter sheet pan will bake up quick (about 14 to 16 minutes)
• A loaf pan will likely take longer (about 22 to 25 minutes)
• Two round 6 x 2-inch cake pans will have a shorter baking time (about 15 to 18 minutes)

For the best results, begin checking for doneness 8 to 10 minutes earlier than the shortest baking time listed for a cake pan on your box. Then add more time as needed.

You’ll know the cake is ready when a toothpick inserted into the center comes out clean.

Wait for the cake to cool completely before digging in!

Storing The Leftover Dry Mix

I recommend putting the remaining mix in a reusable sandwich bag. That way you can toss it into the cake mix box with the directions and ingredients info.

Pro Tip: Write the baking time, temperature, and pan used to bake half of the mix on the outside of the box. That way whipping up the other half will be super easy.