It depends on the bakery/store. I have seen 11x15 side by side to make a full sheet, and I have seen 12x18 side by side. The cake store I use to buy supplies has half sheet boxes that will not fit a 12x18 on the board that fits in it, so the cake has to be an 11x15.
Use what you want as your size and just tell your customers the number of servings rather than the measurement of the cake.
I too am confused on what size a Full Sheet cake is....I even called a couple bakeries to ask what size their full sheet cakes where and they wouldn't tell me, they just told me how many people it would serve. 
So when I baked a full sheet cake, I baked 2 12 x 18s and put them together, but they wouldn't fit ont he full sheet cake board i had bought so i had to trim the edges. So i think a full sheet cake is 2 11 x 15s put together, that would have fit on the board perfectly....
I would just stick to finding out how many people they need to serve and go from there... 
So, if I put 2 11/15 together will that make a full sheet or do I need to do double layers also. I need to serve 100 people.
Lu
I agree with indydebi, you need at least two 12x18s together to feed 100. If you cut one 12x18 cake six by eight pieces, that's 48 pieces. Two of them will give you 96. I usually tell people a 12x18 feeds 36 ... that's cutting six by six. It definitely depends on who's cutting the cake. And how they cut the cake depends on if it's the only dessert offered or if there are other things to choose from.
Oh, if you did two layers of either two 12x18 or 11x15, you'd need two people to lift it!
Could someone tell me the honest to goodness true measurements to a full sheet cake? I have seen so many different opinions on this.
Lu
The reason you see so many opinions is because there is no standard. The standards seem to be regional and personal.
I have done like Indydeb, I don't have 1/4, 1/2, full b/c when someone orders that they don't know how big or small it actually is. I ask them how many people they want to serve. I tell them my serving size and then leave it up to them how many servings they want to order.
This is great information, I'll be making my first 11x15 this weekend. I've been told to only use 1 cake mix, is this correct? Don't know why but I was thinking it would take 2 ( the whole WASC recipe). Wouldn't I need to use the flower nail too?
This is great information, I'll be making my first 11x15 this weekend. I've been told to only use 1 cake mix, is this correct? Don't know why but I was thinking it would take 2 ( the whole WASC recipe). Wouldn't I need to use the flower nail too?
I use 2 mixes for my 11 by 15. One mix would not be thick enough. I don't use a flower nail and it does fine at 325 degrees.
This is great information, I'll be making my first 11x15 this weekend. I've been told to only use 1 cake mix, is this correct? Don't know why but I was thinking it would take 2 ( the whole WASC recipe). Wouldn't I need to use the flower nail too?
Dixiegal01, an 11x15 pan absolutely requires two cake mixes. No, you don't need a flower nail.
This is great information, I'll be making my first 11x15 this weekend. I've been told to only use 1 cake mix, is this correct? Don't know why but I was thinking it would take 2 ( the whole WASC recipe). Wouldn't I need to use the flower nail too?
Dixiegal01, an 11x15 pan absolutely requires two cake mixes. No, you don't need a flower nail.
Absolutely agree. 2 mixes ...325 degrees..... baking strips .... no flower nail.... turns out great.
Quote by @%username% on %date%
%body%