I was thinking about just using boxed cake mix for a 12x18 sheet pan cake. I usually do one of the doctored recipes but I already have so much time needed for this cake I think I am going to just use boxes. They come out good as well. I am just not exctly sure how much batter I will need. I came up with 2 1/2 boxes of mix. Does that seem right? Thanks for the advise.

2.5 is what I use.

A box mix makes 4 1/2 to 5 cups without adding anything to it. A 12x18 pan requires 14 cups of batter so I would do 3 batches per layer.

I use 2 mixes that each have an extender.....it fills up the pan.

Hi ~ I too use about 2.5, it rises just above the edge so I can lay a board across the top, weight it down and then no crown to trim .... nice and even.

I use 3 boxes everytime I make a 12x18 sheet and they have always come out perfect!

I use three boxes as well.

With the cake extende, I use two boxes of the DH mix.

I also use 3 when I use box mixes.