Serving Counts for Wedding Cakes
The number and size of the servings that you will get from
your wedding cake is based on four factors:
1. Which cake-cutting chart is your baker using to determine
the number and size of tiers that you'll need?
2. How high is each tier?
3. Is the top tier included in the serving count?
4. Who will be cutting the cake, and how do they do it?
1.
Cake cutting charts vary, and sometimes by a lot.  I use a
range of servings for each tier, based on a number of charts.
You can choose whether to have more or fewer servings
based on your own situation. (number of guests, if the cake
is the only dessert, etc.)
How tall are the tiers that will be on your cake? Some bakers
use 3" tall pans, then may or may not cut them in half to add
a filling in the middle. Others, including myself, use 2" tall
pans, then put one to three layers of fillings in each tier.
This gives you a tier that will end up being between 3 1/2 to
4" tall. The higher the tier, the more generous the serving
size that will be served to your guests.
2.
The top tier of the cake is traditionally saved for the bride and groom so that they
can save it for the first anniversary if they want to. Because of this, many bakers
don't include it in the serving count, and the couple may or may not be charged for
it. Even if you plan on having me make an anniversary cake for you and you'd like
to serve the top tier at your reception, the reception staff will most likely save the
top tier for you because they're so used to doing it. Make sure that your baker is
not including the top tier in your total serving count, and if they are make sure that
they will alert the staff to serve it.
3.
4.
Of all the factors, this one may be the most important! Your baker can do all the
estimating in the world, but if the person who cuts the cake cuts smaller slices,  
your servings will differ. Because of this, I take cutting instructions with each cake,
and indicate what the size of each slice should be. In addition, because of the size
that I'm estimating for my servings, you'll probably get more, rather than fewer,
servings if someone cuts the slices according to a different cutting chart.

I also indicate that the server should cut the tiers "square," rather than the
traditional round way. If someone cuts the cake "round" anyway, they will get more
servings than I estimate.