Ok.... I am going to make the 1st birthday pirate cake from the new Wilton yearbook for my nephews birthday on Saturday..

It says to use the 15x11x2 diamond pan but I do not have that one and don't really want to buy it for this one cake since its just for my nephews party..

By the Wilton Party serving chart the 8" square pan says it is the same amount of servings , 20 ...but the square takes 4 cups of batter and the diamond takes 7&1/4.. This doesn't make sense to me..

I don't care if the shape is different but will they be close to the same finished size?

Thanks