The age old question…how much buttercream do I need?? For a batch of cupcakes? A 6-inch layer cake? For a wedding cake?!
This post shares everything you need to know to make the perfect amount of frosting for any baking project. It’s basically the frosting version of my cake batter calculator.
The amount of frosting you need varies based on the following factors:
- Size of cake layers
- Shape of cake layers
- Number of cake layers
- Decoration style (semi-naked, smooth, buttercream rosettes, large swirls on top, on etc.)
With the help of my buttercream formula and chart below, you’ll be able to figure it out in a snap!
Does It Matter What Type of Buttercream I’m Using?
This guide can be used for pretty much any type of frosting. Whether you’re using American, Swiss, Italian, Russian, or even German, a cup of frosting is a cup of frosting.
My only note on this is that I find I sometimes need a tiny bit more American buttercream to make a perfectly smooth cake.
If I’m using a meringue based frosting, it usually is a bit easier to smooth and I can use slightly less on the sides of the cake.
How Does this Buttercream Calculator Work?
Creating this chart meant thinking through what we’re trying to calculate.
To know how much frosting we’ll need, we need to use the formula of a cylinder, the formula of a circle, and then back out how many cubic inches are in a cup to get to our answer.
With that in mind, the formula I used is:
Cups Needed = ((area of a circle x thickness of the layer of frosting x number of layers) + (surface area of a cylinder minus top and bottom)) / by cubic inches per cup
Or in terms of numbers for a 6 inch, 2 layer cake, this meant:
Cups needed =((pi x r in2 x .33 in) + (2 x pi x r in x h in x .25 in))/14.4 in3
I had to make some assumptions in this formula, including that the outer coat of frosting will be about 1/4 inch thick, and that the frosting layers inside the cake will be about 1/3 inch thick.
This is based on how I actually decorate my cakes! I love thick layers of frosting inside, just like in my death by chocolate cake shown above.
However, if you use a lot less frosting between your cake layers, or if you want to make a design that requires a lot of extra buttercream (like buttercream rosettes) these numbers might need to be adjusted.
If you aren’t a big fan of math, don’t worry! I’ve used this formula to create a chart below that’s super easy to use. It’ll instantly tell you how much buttercream you need 🙂
Step 1: How Big is the Cake You’re Making?
The size, shape and number of cake layers will impact how much frosting you need.
In general, I find one batch or about 6 cups of frosting is the perfect amount for a 7-inch or 8-inch layer cake that’s decorated with buttercream swirls on top.
I usually have a tiny bit leftover, but it’s just about right. This makes sense based on my calculations below!
Step 2: Use My Buttercream Calculator to Figure Out How Much Frosting You Need
Based on the size of your cake, use the charts below to figure out how much frosting you need. This is just to fill, crumb coat, and cover a layer cake.
Add an addition 1-2 cups of frosting to the numbers below if you want to pipe large buttercream swirls on top of the cake.
Or if you want to make a frosting intensive design like covering a cake in buttercream rosettes, add an additional 2-3 cups of frosting for a cake ranging from 6-8 inches. It sounds insane, but those designs require so much extra frosting!
Step 3: How Many Cups of Buttercream are in One Batch of Buttercream?
Now you just need to figure out how many cups of frosting one batch makes.
My American and Swiss Meringue buttercream recipes both make about 6 cups of frosting.
However, it can vary based on the recipe you’re using.
Most recipe cards list the yield at the top of the recipe card, or will share it in the notes section at the bottom of the recipe card.
Now that you know how many cups of frosting you need, you can back into how many batches of frosting you’ll need to make.
And just like that, you’re ready to make the perfect amount of frosting!!
I’d love to hear if you found this post helpful, or if you end up use it! Tag me @chelsweets and #chelsweets on social media.
You can also download the charts above here!
Wednesday 1st of March 2023
could you clarify where you get this .33 value in this equation? =((pi x r in2 x .33 in x 2
Sunday 5th of March 2023
For sure! The .33 value assumes that the layer of frosting between the cake layers will be about 1/3 inch thick. My cake layers are usually about 1-inch tall, and I find I like that frosting to cake ratio :) Hope that helps, happy baking!
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Thursday 6th of October 2022
I just stumbled upon your website and it is so informative - thank you for posting step by step, recipes and calculations. They are super helpful for beginners like myself. I am attempting to bake my daughter's 1st birthday cake (eggless/nut free w/ buttercream frosting)
My question is how do i calculate the amount of ingredients for the buttercream? According to your above post, for an 8 inch 2 layer cake i will need 4 cups of buttercream. But I also would like some left over buttercream to try and make some design rosettes on top of cake.
Thursday 6th of October 2022
Thank you so much for sharing, you're too sweet! To figure out how many ingredients you need, you just need to know how much frosting whatever recipe you plan to use makes. For example, one batch of my American buttercream recipe (https://chelsweets.com/the-best-american-buttercream-recipe/) makes about 6 cups of frosting. With that in mind, one batch would be perfect for your cake, because you would have enough to frost the cake and have 2 cups leftover for decorating the top of the cake.
Most recipes share how much they make either at the top or bottom of the recipe card. Hope that helps, happy baking!