I am a true rookie at this but want to make a Graduation cake for my sons Graduation party - I have ordered on-line a edible Image for 1/2 sheet cake
Dimensions are 12 1/2" X 8"
I get so confused on what size to make with the pans because they say it has to be on a 1/2 sheet cake size - do I put two sheet cakes together or will this make a crease where the cakes go together - and if I do that how do I make it that it looks flat ?

I should just buy one but out of town family coming in and they love to eat my cakes that I have made in the past but they to me have never been that pretty for a big graduation party - just a bit nervous and such a rookie but want to pull this off. If any suggestion you have I sure would appreciate it- Thanks

There's no industry standard for quarter/half/full sheet. I wish those terms would disappear. All they do is cause confusion.

If your image is 12-1/2 x 8, then your cake simply needs to be bigger than those dimensions.

You don't say what size cake pans you have, but I assume you have 9x13. Two 9x13 cakes, side by side, measure 18x13. Plenty of room for your image.

As long as you carefully level your cakes to the same height, there won't be a crease in the center. Be sure to cover with plenty of icing.

To ensure there's no movement or cracking of the icing, use 1/2-inch thick foamboard as your cake board. Cover with white or clear Contact paper or foil. Cut the board to be at least 2 inches larger than the cake on all sides. So, if your cake is 18x13, cut your board to be at least 22x17.

........DianeLM said:.......wish those terms would disappear. All they do is cause confusion............

A truer statement there is not I agree w/the advice she gave you. If your pan is indeed a 9x13 you will need 1& 1/2 cake mix batters to fill it. This is a perfect time to use the *original* WASC recipe ( http://cakecentral.com/recipes/7445/the-original-wasc-cake-recipe ) as it makes that much batter and is sooooooo YUMMY It can be made in *any* flavor cake you want.
When the cake comes out of the oven it should be perfectly level with the top of the pan. If not, just put a cookie sheet over the cake and gently press down to level it. That way both cakes will be exactly level and pushed up against one another no 'seam' will be seen.

Adding to kakeladi's tips for leveling the cakes... When you're ready to assemble, flip the cakes so the bottoms become the top. You'll have a nice, flat surface.

I just want to thank you for your helpful tips - so very kind

Post a pic of your son's cake!