One question I get asked quite regularly is “how much fondant do I need to buy to cover my cake?” So I decided to create a calculator where you enter the size of your cake and it’ll give you an estimate of the amount needed.

Calculating the amount of fondant needed isn’t an exact science as it depends on how thick you want it to be, how good you are at rolling it out to the exact shape you need it and how much excess you’ll have (I usually roll mine out to be about 1cm wider than it needs to be all around, which then allows me to get it nice and smooth and to trim it neatly at the base of the cake).

This calculator gives you an indication of how much you need to buy so you know you’ll have enough, but should prevent you getting carried away and buying far too much.

It assumes your fondant is rolled out to be 4-5mm thick and you have 1cm excess fondant all the way around the cake.

In order to calculate the amount of fondant then you’ll need to measure the height of your cake. This can be a bit tricky if you’ve not made it yet! As a guide, if you’ve made one of my vanilla or chocolate birthday cakes then a 2-layer cake sandwiched with buttercream and a thin layer of buttercream on top will be about 9cm high and a 3-layer cake about 13.5cm high.

# Round Cake

Cake Diameter (cm)

Cake Height (cm)

Amount of fondant = 0 grams

# Square or Rectangular Cake

Cake Size (cm)

x

Cake Height (cm)

Amount of fondant = 0 grams

Ian Morgan says

Wonderful calculator, but how thick do you roll the fondant out to?

Charlotte Oates says

I roll mine to be about 4-5mm thick.

Polly Watson says

This is a Great help – thank you very much!

Pam says

Thank you, that will save a lot of guess work.

Sandra Jones says

Thank you for the fondant calculator really helpfull

Claire says

Really helpful article, thanks!

Kate - Gluten Free Alchemist says

There are definitely times when I have needed a fondant calculator! Bookmarked xx

Charlotte Oates says

I hope you fine it useful 🙂