Will a double layered 9 x 13 sheet cake feed 60 people or should I go up to 11 x 15? This will be a party cake. I was looking at wilton's chart but was skeptical. TIA!

on the 9x13, if you fudge a tad and cut the 9" side four times making five even rows of cake, you'll have 5x13 = 65 servings which is just a fraction under the traditional serving size

on the 11x15, if you don't fudge and cut the 11" side four times making five even rows of cake you'll have 75 servings --

these are traditional size servings of 1x2x4 -- I never do party servings --

but if you cut the 11" side three times making 4 even rows of cake you'll have exactly 60 and they will be larger servings than the traditional size -- 

decisions decisions 

Thank you! I'm going to quote the customer both and let her decide how much left over cake she wants. ha! 

@-k8memphis Do you quote by cake slice? If so, so you quote by the maximum cake slice that the chosen cake size would typically feed?

I know you are asking K8 but thought I ‘d pipe up   Yes charge by the “slice” & all that  size cake serves even if you sculpt it