Sheet Cake Sizes: How Much Cake Do You Need?

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If you have an event involving many people, you may be at a loss as to what type of cake would best serve all your guests. 

Well, worry no more! A sheet cake will do the trick. But since there are many sheet cake sizes available, you must first be sure what size will be needed to feed all the people you expect at the event. 

This article explores various aspects of sheet cakes, from sizes to making them at home to purchasing them at the store. Let’s discover what you’ll need and how to make one if you want to treat your guests to a homemade sheet cake. 

What Is a Sheet Cake?

Frosted sheet cake

Also called a slab cake, a sheet cake is a cake baked in a flat, rectangular cake pan. You can serve the cake with frosting or layer it with a filling and then frost it. 

People like sheet cakes because they are easy to customize and decorate. You can add as many decorations and customizations as you want on the flat top, and there’s plenty of room for names and dates. 

They are also easy to move around since they don’t require a lot of structural support or layering. 

Sheet cake slices are also neater, easy to cut, and easy to serve. 

Most people bake sheet cakes in a single layer. Supermarkets and stores sometimes bake two layers, depending on the order. A third layer is also possible

How to Make a Sheet Cake With Cake Mix

If you have your cake mix ready, it’s easy to make a sheet cake. 

  • Preheat the oven to 350°F (this may vary depending on your cake mix).
  • Generously grease your sheet cake pan (bottom and sides).
  • Pour the cake batter into the prepared pan, spreading it evenly into one layer. 
  • Bake the cake for 32 to 38 minutes until it is thoroughly cooked (a toothpick dipped into the cake should come out without cake mix).
  • Remove the sheet cake from the oven and leave it to cool down on a wire rack while still in the sheet pan.

How Big Is a Sheet Cake?

The size of a sheet cake varies depending on the pan used to make it. The pan sizes vary from one manufacturer to another. 

The most common full sheet cake pan sizes in length and width are: 

  • 16″ x 24″
  • 18″ x 24″
  • 18″ x 26″

The height or depth of the sheet pan usually ranges between one and four inches.

How Many People Does a Sheet Cake Feed?

The number of people a sheet cake feeds varies based on factors such as:

  • The size of the sheet cake pan
  • The number of layers the cake has
  • The cutting pattern used by the cake cutter
  • Second helpings
  • The type and amount of food people have eaten before or with the cake
  • The type and amount of icing

A cake with two layers will serve more people than a cake with only one layer. If the cake cutter makes irregular cuts, the cake is likely to serve fewer people. 

People who have just eaten a heavy meal shortly before the cake are less likely to eat a lot of cake, especially if the food is too sugary or sweet. 

A cake with a lot of sugary icing will serve more people because it has more volume. Again, more sugary stuff means each person will likely want to eat a smaller piece, so the cake can serve more people. 

The best approach to determine the estimated number of people your sheet cake will serve is to do a little math.

  • Calculate the area of your cake based on the length and width of the cake pan. For example, if your full sheet cake pan measures 18″ x 24″, the area of the cake will be:

18″ x 24″ = 432 square inches. 

  • Estimate the size of each cut or serving. This is usually 2″ x 2″ or 2″ x 3″ per person. The area of each serving will be:

2″ x 2″ = 4″ (using the first values)

  • Divide the area of the cake by the area of each cake cutting:

432÷4 = 108 people. 

A full sheet cake from a pan measuring 18″ x 24″ will serve 108 people, give or take—depending on the abovementioned factors. 

How Many Cake Mixes for a Sheet Cake? 

You’ll need four to five full cake mix boxes to fill one full sheet cake pan to make a one-inch layer sheet cake if the pan is 18″ x 26″ or 18″ x 24″. 

How Big Is Half a Sheet Cake?

Peanut butter sheet cake

A half sheet cake size is half a full sheet cake, which you obtain by cutting the full version in two equal parts or making one from scratch using a half-sheet cake pan

Since sheet cake sizes vary, you might not always find a half or quarter sheet cake pan that will be a whole-number divisibility multiple of the full sheet cake pan. 

As such, you can only truly make a half sheet cake or quarter sheet cake by cutting it from a full sheet cake. 

How Many People Does a Half Sheet Cake Feed?

Most half sheet cake pans have the following dimensions:

  • 12″ x 16″
  • 12″ x 18″
  • 13″ x 18″ 

If your pan measures 12″ x 16″, and the pieces measure 2″ x 2″, you calculate the number of people it can serve as: 

12 x 16 = 192. 192 ÷ 4 = 48 people. 

How Many Cake Mixes for a Half Sheet Cake?

Two or three boxes of cake mix weighing 2 pounds each will be enough to make a one-inch layer of a half sheet cake if the pan is 13″ x 18″. 

How Big Is a Quarter Sheet Cake?

Sliced peanut butter sheet cake with toppings

A quarter sheet cake is a fourth of a full sheet cake. You can also determine the size based on the cake pan size. 

Quarter sheet cake pans usually have the sizes below:

  • 8″ x 12″
  • 9″ x 12″
  • 9″ x 13″

How Many People Does a Quarter Sheet Cake Feed?

As with the full sheet cake and half sheet cake, you can calculate the number of people you feed with a quarter cake as follows:

The area of the cake, for example 9″ x 13″ = 117 square inches, divided by the area of each cutting, for example 2″ x 2″ = 4″. 117 ÷ 4 = 29.25. The cake will feed about 29 people. 

How Many Cake Mixes for a Quarter Sheet Cake?

One to two boxes of cake mix will fill a quarter sheet cake pan if it measures 8″ x 13″ or 9″ x 13″. 

How to Frost a Sheet Cake

You can frost a sheet cake using a large icing spatula, either on the sides and the top or just the top. For a 9″ x 13″ sheet cake, you’ll need about three cups of frosting. You will need extra frosting for decorating and piping. 

Pro tip: If you freeze the cake first, it will make frosting and decorating it easier.

How to Cut a Sheet Cake

You should always use a clean, long, thin, plain-edged knife to cut a sheet cake. Use the calculation guides above to determine how many pieces to cut. You can map these square shapes out on the top of the cake before cutting.

Remember to clean the knife after each cut with a clean towel to ensure the next cut is smooth and even. 

How Much Is a Sheet Cake?

You can spend between $25 and $120 for a full sheet cake, depending on the seller, the decorations, and the number of layers. 

For example, a full sheet cake will cost you:

  • $100 at Publix
  • $120 at Whole Foods
  • $80 at most local bakeries
  • $45 at BJs
  • $50 at Walmart 

Note that prices may vary based on several factors, even at one retailer. 

How Much Is a Costco Sheet Cake?

A decorated half sheet cake atCostco will cost you $18.99, whether white or chocolate. Costco estimates it to have 48 servings. You can get the full version for $55.