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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!

Denise Vasquez

Thursday 27th of February 2025

Thank you for sharing I make starting to make at home to get really good at it. Made a few petty good but the frosting needs work in the area of the amount to use a 3 layers 3.

Mariko

Thursday 13th of February 2025

This is soooo helpful! Thank you so much for doing all the work for us and sharing it!

Chelsweets

Sunday 16th of February 2025

So glad you found this post helpful Mariko! :) It took quite a bit of time to calculate it all! Thank you for sharing!!

Mickey launch

Sunday 2nd of February 2025

Can 1kg of icing and 1and half of butter be okay to make a butter cream icing for a 7 inches love cake

Chelsweets

Sunday 2nd of February 2025

Hi Mickey,

It's better to measure by volume for this, because different types of frosting weigh different amounts! What type of frosting are you using? That sounds like it should definitely be enough for a 7-inch layer cake though!

Mickey launch

Sunday 2nd of February 2025

@Mickey launch, I don't understand pls tell me is it okay to use 1kg and 1and a half in butter cream icing for love cake

Fresh Strawberry Buttercream - Liv's Little Muffins

Monday 13th of January 2025

[…] sheet cake with this amount. For other sizes or layer amounts, I highly recommend checking out Chelsweets buttercream calculator. It’s a great easy tool and she has everything you can think of in this […]

Morgan

Thursday 4th of July 2024

How much buttercream should I use for an 8 inch hemispherical cake? I would need the buttercream for the inside layer of cake and to make crumb coat

Chelsweets

Sunday 7th of July 2024

Hi Morgan,

Do you mean just to coat the outside of the cake? The formula for surface area of a hemisphere is 3?r2, so you'd need the multiple the thickness of the layer of frosting in inches x 3?r2. If you wanted it to be 1/4 inch thick, it would be 0.25 x 3 x 3.14 x 16 = 37/14.4cubic inches per cup = 2.7 cups of frosting. Feel free to adjust the thickness as needed. Hope that helps, happy baking!