How many party cake servings for a 2 layer? I get different answers at about every site I check out.

Wilton says 45 servings. Their servings recommendations are pretty small though.

For a single layer 9x13 aka quarter sheet, you will get 24 (2x2x2high) industry standard size servings.
For a two layer 9x13 aka quarter sheet, you will get 48 (1x2x4high) industry standard size servings.
Party size servings are 2x3x2high for single layer, so you get approx 18 servings in a 9x13.
Party size servings are 1.5x2x4high for two layer, so you get approx 36 servings in a 9x13.
Family size servings are 2x4x2high for single layer, so you get approx 12 servings in a 9x13.
Family size servings are 2x2x4high for two layer, so you get approx 24 servings in a 9x13.

Someone please correct me if my math is wrong.

For visual reference, Family size is on the left, Party size in the middle and Industry standard size (also used for pricing) on the right.
http://www.cakecentral.com/modules.php?name=gallery&file=displayimage&pid=88648

Are you serving it or pricing it?

If you're serving it, it can have as little as 2 and as many as 50.

If you're pricing it, determine what your standard serving size will be. I don't believe in "party" and "wedding" servings.

For example, for pricing, I go by 1x2x4 as the serving size. Here's a pic of how big that piece is: http://www.cakecentral.com/modules.php?name=gallery&file=displayimage&pid=1156785

doing the math is easy on a rectangle cake. To cut a 9x13, 2 layer cake, into 1x2x4" pieces (and I always round down to even numbers to make it easier), you would cut 8 rows (the 9" side cut into approx 1" rows) by 6 columns (the 13" side cut into approx 2" columns). 6x8 = 48 pieces.

I tell the client, "You can get 35-45 pieces, depending on how you cut it. The cost is blah-blah-blah."

If you use different dimensions other than 1x2x4, then just do the math the same way to determine the number of servings.

But I STRONGLY suggest you pick a serving size and stick with it TO DETERMINE PRICING.

You serve cake like I do, Debi! At least when it comes to a 9 x 13 serving 2!

The info has helped a LOT! THank you SO much... I blow at math
It'll be a tall 2 layer as I'm using white chocolate mousse w/ strawberries. It always ends up taller than I think it's gonna end up w/ that filling. The cake I did for my daughter's bday was ridiculously tall w/ 3 layers plus that filling. The 9x13 will give very generous servings for 20... it puts my mind at ease.
Thanks for all the input!

Melanie Mc.