To calculate size(s) of cake(s) required please see tables below.
These are a guide only and more generous portions may, of course, be cut. They are based on my own cake tins, and since manufacturers produce non standard tins the figures below may not be applicable to tins other than my own.
These assume that the cakes are marzipanned and sugarpasted. The top tier, for wedding cakes, should not be included in the portion calculation if it is to be kept for the first Anniversary or Christening.