Buttercream Calculator
Choose what you are covering and the size of the cake for the buttercream and its ingredients.
Choose what the buttercream is for.
Reference and detail
Covering takes far more than filling
Filling between two layers needs a fraction of what a full coat plus piping takes. Running out halfway through crumb-coating is a miserable way to find that out.
One part butter to two parts icing sugar
That ratio pipes cleanly and holds its shape at room temperature. More sugar sets firmer and sweeter; less is softer and needs a cool room.
Beat the butter first
Several minutes of beating on its own makes the butter pale and light, and the finished buttercream noticeably smoother and less sweet-tasting.
Questions and answers
Questions about buttercream quantities
How much buttercream do I need between cake layers?
Enter your tin size and number of layers above and choose 'filling', the amount depends on the area of each layer and how many joins there are, since a two-layer cake has one filling layer but a three-layer cake has two.
How much buttercream do I need to cover a whole cake?
Choose 'full cover' above and enter the finished height of the cake as well as the tin size, covering the sides as well as the top needs noticeably more than filling or a top-only finish, because it depends on the cake's perimeter and depth, not just its area.
What ratio of butter to icing sugar makes British buttercream?
One part soft butter to two parts icing sugar by weight is the standard British buttercream. Beat the butter alone first until pale, then add the sugar in stages so it doesn't puff everywhere.
Should I make extra buttercream just in case?
Yes, make around 10% more than the calculator suggests. Running out part-way round the side of a cake is far more awkward to fix than having a little left over.
Why has my buttercream gone soft and slack?
Warm kitchens soften buttercream quickly. Chill the crumb coat before adding the final layer, and keep the bowl out of direct sun or off a warm worktop while you work.