I'm curious as to how many servings for the odd size pans that are not listed in the Wilton serving chart. I need this info in order to price my cakes. Just wondering what everyone else does. Like 4, 5, 7, 11, 13, 15 inch rounds?

Most serving sizes are a good guess at best since most people don't have a ruler in hand when they are cutting and serving a cake.

That said, I think it would be a good guess to pick a number in between. For instance, an 11 inch cake would serve 27, the number inbetween a 10-inch serving of 24 and and a 12-inch serving of 30.