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How Much Buttercream Do I Need?

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:

With the help of my buttercream formula and chart below, you’ll be able to figure it out in a snap!

image of a buttercream cake being frosted with sharp edges and smooth sides to show How to Frost a Cake Smoothly

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 left over, but it’s just about right. This makes sense based on my calculations below!

image of a gluten free funfetti cake that's been decorating with buttercream stripes and a pink drip

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 additional 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!

image of a chart showing how much buttercream you need to frost a round layer cake
image of a chart showing how much buttercream you need to frost a square layer cake
image of a chart showing how much buttercream you need to frost a cupcakes

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.

image of purple frosting in a bowl that's been stirred by hand to make it super smooth after it had developed air bubbles from sitting

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 using it! Tag me @chelsweets and #chelsweets on social media.

You can also download the charts above here!

Arianna

Saturday 8th of June 2024

Hi good day. I love your use of mathematics in real life scenarios!! Makes me appreciate learning all those formulae in school. Can you clarify what the height (h) of the cake would be in the part of the formula (2 x pi x r in x h in x .25 in) please?? Also, where in the formula would I multiply by the number of layers? I didn’t see it in the formula above Could you use an example, say 10 inch 3 layer round cake, to show me please?? Thank you.

Chelsweets

Sunday 9th of June 2024

Hi Arianna,

Totally agree!! Love putting mathematics to good use :) The height of the cake is roughly how tall you think the cake will end up being. This can vary based on the recipe you use, but my cake layers are usually about 1 inch tall, and i make the frosting layer about .25 inches thick, so a 4 layer cake would be about 5 inches tall. Hope that example helps!

To adjust the amount of layers, you'd change the 2 in this equation to be however many cake layers you have: (2 x pi x r in x h in x .25 in))

For example, if you had 4 cake layers, the equation would look like this: (4 x pi x r in x h in x .25 in))

A 10 inch, 3 layer cake would be: ((3.14 x 5 in2 x .33 in) + (3 x 3.14 x 5 in x h in x .25 in)). You'd have to add in the height you think the cake will be. Hope that helps, happy baking!

Suzanne Marek

Tuesday 21st of May 2024

Is there any where that you have calculations for the amount of frosting needed to crumb coat & frost a 1/2 sheetcake?

Chelsweets

Sunday 26th of May 2024

Hi Suzanne,

Sadly I haven't done the calculations for that yet! I did make a sheet cake guide, but it just covers the amount of servings and the amount of batter you need for different sized sheet cakes. I'm so sorry! That will have to be my next math project!!

Delana

Monday 20th of May 2024

Hi I'm looking forward to making your buttercream recipe. I will be making 72 cupcakes for my daughter's wedding with tall swirls on top and wanted to know if you could tell me how many cups of buttercream I would need for that?

Chelsweets

Sunday 26th of May 2024

Hi Delana,

I'd say you'd probably need about 12 cups of frosting! But it can vary a bit based on how tall the swirls are. Hope that helps, happy baking!

Anastasia

Wednesday 3rd of April 2024

How do i convert this into grams?

Chelsweets

Sunday 7th of April 2024

Hi Anastasia,

It can't really be converted to grams because different types of buttercream weigh different amounts :/ Unless you weigh out 1 cup of the frosting you plan to use and then convert it that way! It can be converted to ounces though if that helps?? So sorry!

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