Figuring out serving sizes for cakes can be mind boggling and intimidating so this chart should help you find it easier to figure out how much you will need to serve your guests.
This chart shows TRADITIONAL wedding servings cut at 1"x2"x4"
This chart shows TRADITIONAL party servings cut at 1.5"x2"x4".
This chart shows rounds cut at 2"x2"x4" servings.
Here is another way of seeing slices. Keep in mind that hight can change on amount of layers. Standard finished layer sizing is usually 4"-5" tall(including filling).
These are "traditional" serving sizes that are standard in the cake industry....and what might be traditional to some is not always traditional to others, your family or for your event. My family loves cake and we like our portions bigger than the above sizes.
Adults eat larger portions than small children so knowing what type of guests you are having helps too. If you have a general idea of the slice size you would like to serve your guests you can calculate your portion sizes by the circumference of the pan sizes. Hope that helps!
***Thanks Cyrus for inspiring me to get these charts done! ***