I'm going to make a birthday cake with a 12x18x2 sheet cake pan and it requires 14 cups of batter. I'm considering making a chocolate/yellow marble cake. So, how many batches of chocolate batter will I need and the same with the yellow? Any help?

How many batches is going to depend on your recipe. I know for instance that Duncan Hines boxes with an additional egg and box of pudding yeilds 6 cups for me. I have had Betty Crocker yeild 4 cups depending on flavor. And all of my scracth recipes are somewhere in that range. Depending on what you are using for your cake you may just have to make a batch and measure it out. If you have any extra batter make some extra cupcakes for yourself or freeze them for later use in an order.

Leily

Each box mix makes 5 to 5-1/2 cups of batter. So you will need to make about 3 bix mixes all together.....you can make cupcakes or a small cake with any left over batter.

You could do 2 batches of yellow and one of chocolate and then marble the two together!