Hello! I have a full sheet cake order that I am currently working on. I have never made a full sheet cake before. I have a lot of questions!! From what I have gathered from this forum is that I can use 4 - 9x13" pans to make my full sheet cake. They want half chocolate and half vanilla. What I did was made 4 separate cakes in 9x13 pans. Now that I am to assembly stage I am a little nervous. They are domed so I am guessing I need to shave them down to be flat? Also my full sheet cake board (bought from Giant Eagle) is 17x25! That will not fit all 4 cakes side by side. More like 3. My original plan was to have 1 chocolate 1 vanilla and cut the other 2 in half then piece together! Will I be losing a whole lot of cake? I need to feed 72 people for a preschool graduation. Thanks so much for the help! I apologize for all the questions!

3 still serves 75.  You'll need to make a larger board.

If you carve all 4 down to 16X24, it'll serve 96.

If you stack 2 on 2 for double layer, servings would be sliced 1x2x4 instead of 2x2x2.

CWR41 is right on all counts.  Your board will not fit 3 cakes.  The only way to make them fit is to put two next two each other and stack the other two on top and then trim the cake down to fit the board you have.  Is the board strong enough to support that weight?

Thank you for your help!! I was able to fit 3 cakes on the board somehow! I still had some room around the board to work with too. Sheet cakes are probably the worst experience yet! From trying to hunt down boxes and boards, to not having the correct pan(and no flower nails OR heating core), to trying to figure out just what size is the "real full sheet cake" size! Haha! I will be happy to not see another sheet cake for a very long time! Plus I am not big on decorating fine detailed things either and with a giant flat surface you have no room for anything other than detailed decorating! Give me some layers to work with!!! Haaa. Thanks again!

Wow, I don't know what kind of cake magic you pulled off there, but good for you!  The balloon and the pendants look great :)

Yes!! While reading all the threads in this forum I found out quickly that everyone has a different idea of what the size of sheet cakes are!! Haha. So after a week of sifting through advice on here, I went to Giant Eagle and asked to buy a full sheet cake board. Then I went from there. Whatever would fit on the board was my full sheet cake as well!! Next time I will double my batch of batter so that it rises higher in my 9x13 (It has super high sides!) so that I am getting more cake!! Do you think that would cook evenly enough or would it be too thick? It always seems like most sheet cakes are pretty thick in size!

Measure the sides (the depth) of your pan.  generally it is better to bake a 2" tall cake and if you want it taller bake another layer.  Anything taller than a 3" cake takes extra time and care to bake up properly. 

Many people think of a sheet cake as just an iced slab of cake without filling.  I always torte and fill :)  Then of course there are those who do 'kitchen cakes' aka: wedding sheets etc.  Those generally are two 2" layers - one of top of the other - with filling so the cut pieces look just like the wedding cake servings.   Basically it just depends on how many servings you need.