Figuring out how much frosting to make for a layered cake can be tricky. You want to have enough frosting to fully cover the cake with a nice, even coat, but not so much that you end up wasting excess frosting. For a 10 inch two layer cake, you typically need around 4 cups of frosting total. Here’s a more detailed breakdown of how to calculate exactly how much frosting you need for your specific cake.
Calculate How Much Frosting is Needed for Each Layer
The first step is to calculate the surface area of each layer of the cake. Here’s the math:
- For a 10 inch round cake layer:
- Area of a circle = π x radius2
- Radius of a 10 inch cake = 5 inches (half the diameter)
- So area of each layer = π x 52 = π x 25 = 78.5 square inches
Since this is a 2 layer cake, you need frosting to cover 2 rounds of 78.5 square inches each, which is 157 square inches total for the top and bottom of the layers.
A good rule of thumb is that you need around 3/4 cup of frosting to cover every 25 square inches of cake. So for 157 square inches:
- 157 square inches / 25 = 6.28 portions
- 6.28 x 3/4 cup = ~4.7 cups of frosting for the layers
Round up to 5 cups of frosting to fully cover the top and bottom of both layers.
Calculate Frosting Needed for the Sides
Next, you need to calculate how much frosting is needed to cover the sides of the 2 layer cake.
The height of both layers combined will be around 2.5-3 inches tall. Let’s assume 3 inches for this calculation. To calculate the surface area of the sides:
- Circumference of a 10 inch circle = π x diameter = π x 10 inches = 31.4 inches
- Height of sides = 3 inches
- Surface area of sides = Circumference x Height
= 31.4 x 3 = 94.2 square inches
Using the rule of 3/4 cup frosting per 25 square inches, for 94 square inches of sides:
- 94 square inches / 25 = 3.76 portions
- 3.76 x 3/4 cup = ~2.8 cups of frosting for the sides
Round up to 3 cups of frosting needed to cover the sides.
Total Frosting Required
Add up the frosting needed for the layers and sides:
- Layers: 5 cups
- Sides: 3 cups
- Total Frosting Required: 8 cups (or 2 quarts)
So for a 10 inch two layer round cake, you’ll need around 8 cups (or 2 quarts) of frosting total. This will provide full coverage on the top, bottom, and sides of the cake.
Tips for Working with Frosting
Here are some helpful tips to ensure you have the perfect amount of frosting:
- Start with slightly less frosting than calculated as a base coat, you can always make more.
- Reserve about 1 cup of frosting to use for decorating and piping details.
- Only frost the sides and top border with the base coat, then chill the cake before the final coat.
- Use an offset spatula to evenly spread frosting and get a smooth finish.
- Keep unused frosting refrigerated in an airtight container for up to a week.
Frosting Recipe for 8 Cups
Once you know how much frosting you need, here is a recipe to make 8 cups of fluffy buttercream frosting:
Ingredients
- 4 sticks (1 lb) unsalted butter, softened to room temperature
- 8 cups (1 lb) confectioners’ sugar, sifted
- 1⁄4 cup heavy cream or milk
- 2 tsp vanilla extract
- 1⁄4 tsp salt
Directions
- In a large bowl using a hand mixer or stand mixer fitted with a paddle attachment, beat the butter on medium-high speed until smooth and creamy, about 2-3 minutes.
- With the mixer running on low, gradually add in the confectioners’ sugar, about 1 cup at a time. Scrape down the sides of the bowl as needed. Once all the sugar is incorporated, beat on high for 2 more minutes.
- Stream in the heavy cream and vanilla extract and mix until fully combined. Add the salt and mix again for another minute. Frosting should be light and fluffy.
- Use the frosting immediately or store covered in the refrigerator for up to 1 week. Let chill in the fridge for 30 minutes before using again. Beat with a mixer for 1 minute to restore texture.
Add in Optional Mix-Ins: For variation, you can add 1/2 cup cocoa powder for chocolate frosting, or 2-3 tablespoons of fruit puree for a fruit flavored frosting.
Frequently Asked Questions
Should I frost the cake layers before stacking?
It’s best to frost each layer individually first before stacking. This “crumb coats” the cakes and prevents crumbs from getting into the frosting layer. Chill the crumb coated layers for 15-20 minutes before stacking and frosting the outside of the cake.
How much frosting do I need for a sheet cake?
For a standard half sheet cake (18×13 inches), you’ll need about 4 cups of frosting to fully cover the top and sides. A full sheet cake (18×26 inches) will need around 8-10 cups of frosting.
Can I double or halve this recipe?
Yes, this buttercream recipe can easily be doubled, tripled etc if you need more frosting. Likewise, you can halve it if you only need 4 cups. Just maintain the same ratios of butter, sugar, cream, and vanilla.
Can I freeze leftover frosting?
Absolutely! Frosted cakes and extra frosting can both be wrapped tightly and frozen for 2-3 months. Thaw overnight in the fridge before using again.
What’s the shelf life of buttercream frosting?
Properly stored in an airtight container, buttercream will last for up to 1 week in the refrigerator or up to 2 months in the freezer.
Is there a dairy free version?
Yes, for dairy free buttercream, substitute the butter with non-hydrogenated vegetable shortening. You can use almond milk or dairy free creamers instead of heavy cream as well.
Conclusion
Figuring out exactly how much frosting you need for a layered cake can seem tricky, but following a few simple calculations takes the guesswork out. For a standard 10 inch two layer cake, you’ll want around 4 cups of frosting total, divided between coating the cake layers and frosting the sides. Making a large batch of buttercream from scratch allows you to decorate generously. And saving any extra in the fridge or freezer means you’ll have frosting ready anytime a cake craving strikes.
