OK, this is bothering me. I use the wilton party cake chart, and it gives 20 servings for both 8" round and squares. Yet the square is bigger. If you look at the wedding size guide, an 8" round is 24 servings, while a square yields 32. That's another third more. Is it because you lose some cake when cutting a round cake? How many party servings are really in an 8" square and round?
Earlene's chart is roughly similar to Wilton's Party chart, and she gives 15 servings for an 8" round and 24 servings for an 8" square. HTH!
I go by the number of recipes/mixes used to make a cake. An 8 in square 2 layers takes 2 mixes, an 8 in round 2 layers takes 1 1/2 mixes. For weddings i figure 20 servings per mix, for parties 15.