Cake wraps are a wonderful thing when you consider the options with edible printing! The entire cake becomes your canvas instead of only the top of the cake. But just how much canvas do you have to work with? With a little bit of math (or the cheat sheet you can download below) you can find it out easily!

Perimeter: the Hero of the Day for Sheet Cakes

The perimeter of any shape is how long the edge is. This is easy to visualize with a sheet cake.

Take a look at the image here. The perimeter is the total length of the four sides. From this we can use a little bit of math to figure it out:

Length + Width + Length + Width = Perimeter

To simplify the math, we can combine a couple of the numbers:

( 2 x Length ) + ( 2 x Width ) = Perimeter

Let’s add some real world numbers to this so it makes more sense. For this example, we will use a quarter sheet cake:

First, the formula:

( 2 x Length ) + ( 2 x Width ) = Perimeter

Now, replace the Length and Width with your real numbers:

( 2 x 9.5” ) + ( 2 x 13.5” ) = Perimeter

I added 0.5” since the cake has a 0.25” thick layer of icing on it. This will change based on how thick your icing is. Keep a tape measure on hand in the kitchen!

Next, work the math:

( 19” ) + ( 27” ) = 46”

So if your goal was to wrap a single image around the edge of a quarter sheet cake with a 0.25” thick layer of icing, you would need an image that is 46” long.

That’s it, seriously! That is all there is to it. Our next example will use a round cake.

Circumference: the Hero When the VILLAIN is a Circle

Circumference is the very geeky term used to describe how long the edge of a circle is. For our needs, circumference is the same thing as perimeter. Don’t let the formula scare you, I’ll show you how to work the math easily!

2πr = Perimeter or Circumference

Ok, I get it, that funny symbol in the middle looks strange. It’s name is Pi. Don’t get hung up on that, just remember that Pi equals 3.14. You also know why March 14th is called Pi Day now (3-14).

What about radius? That is simply the diameter (the width of the circle) divided by 2.

Let’s add some real world numbers to this so it makes more sense. For this example, we will use a 6” round cake:

Before we can work the formula, we need to convert the diameter to a radius by dividing it by 2.

6.5” Diameter / 2 = 3.25” Radius

I added 0.5” since the cake has a 0.25” thick layer of icing on it. This will change based on how thick your icing is. Keep a tape measure on hand in the kitchen!

First, the formula:

2πr = Circumference

Now, replace Pi and the radius with your real numbers, and work the math:

2 x 3.14 x 3.25” = 20.42”

So if your goal was to wrap a single image around the edge of a 6” round cake with a 0.25” thick layer of icing, you would need an image that is 20.42” long.

How Many Icing Sheets do I Need?

This one is easy for a sheet cake since you can measure the side. For round cakes, you need to look at your circumference. We’ll look at the 6” round cake again.

20.42” is the circumference of the cake. The printable area on Icing Images Premium Icing Sheets depends on if you are using Premium Smalls (based on US letter paper) or Premium A4 (based on European paper).

Premium Small: 10.75”

Premium A4: 11.375”

Divide your circumference by the printable area, and that will tell you how many sheets you need:

20.42” / 10.75 = 1.9 Premium Small sheets

20.42” / 11.375 = 1.8 Premium A4 sheets

If you do a lot of cake wraps, you might find that using Premium A4 sheets are best since they are a little longer than Premium Smalls.

A Cheat Sheet for Common Sizes

Here is a printable cheat sheet for you.