Cake Size Calculator — Servings

How the size is calculated

The calculator starts from the number of guests and the slice size, then converts them into the surface area you need. From that it derives a suitable diameter for a round cake and a side length for a square one.

The estimate is based on a slice of about 30 cm² for a normal serving, which matches a typical party portion.

What you enter and what you get

Enter the number of guests and choose the slice size. The calculator shows the required surface area, the diameter of a round cake, the side of a square cake and how many slices you get from a standard 24 cm cake.

This lets you see at a glance whether your planned cake is enough or whether you should go a size up.

Height affects how far it goes

A tall layer cake serves more people than a low cake of the same diameter, because the slices can be cut thinner. Keep this in mind if you make a rich, multi-layer cake.

Chocolate and heavily filled cakes are often served in smaller slices than light sponge cakes.

Party tips

Allow a little extra in case some guests want a second slice or unexpected visitors arrive. Any leftover cake keeps well in the fridge for the next day.