My avatar is a 6" and 10" cake, I baked 4 cakes and torted each one. then placed filling between them when I stacked. The bottom ended up being 4" tall and the top 4" tall.
Here is my question,
Does that end up being 40 servings or 80 servings?
I thought it was 80, but now I am not so sure. Maybe I am just having one of those days!
All of my cakes are 4" tall as well. I get anywhere from 6-8 servings from a 6" round and 28-30 servings from a 10" round, so that would be about 40 servings to me. It all really depends on your serving size. HTH
Two popular serving charts:
http://www.wilton.com/wedding/wedding-cakes/wedding-cake-data.cfm (wedding industry standard)
http://www.earlenescakes.com/ckserchart.htm (slightly larger servings)
I would say about 10 servings for the 6 inch and 30 for the 10 inch. So 40 sounds about accuate.