How much wedding cake do you need?
Not every guest will take cake, particularly when it follows a full dessert or sits beside other evening sweets. If cake is the main dessert, larger portions and a little more contingency are sensible. If you want to keep a tier, do not count it in the servings available on the day.
Why tier charts disagree
Bakers use different recipes, heights and cutting guides. A rich fruit cake may be served more narrowly than a light sponge. Square cakes usually yield more portions than round cakes of the same width. Use this estimate to begin a conversation rather than to instruct the person making your cake.