You can use two cake recipes for that size pan.
A 12" x 18" cake pan will make 72 servings.
If you are using a 2" deep cake pan you would need 13.5 cups of batter.
It depends on how deep the cake pan is.
For a 12x12x3-inch cake pan, you'll need approximately 9 to 10 cups of cake batter. This is based on the volume of the pan, which is about 432 cubic inches. Depending on the recipe and the density of the batter, adjusting slightly may be necessary, but this amount should fill the pan adequately without overflowing.
1/2 full
A 16x16x2 cake pan has a volume of 512 cubic inches (16 x 16 x 2). Cake batter typically weighs about 0.5 to 0.6 ounces per cubic inch, so the pan can hold approximately 256 to 307 ounces of cake batter. This translates to around 16 to 19 pounds of batter, depending on the specific density of the cake recipe used.
6 cups for one layer
The boxes I checked said one box would make a 13x9, so you will need about 1 1/2 boxes for a 12x18. Assuming the pan is deep enough you could use two boxes for a one layer 12x18 or you may want to make a two layer cake using 1 1/2 box per layer.
It will probably take 1-1/2 boxes. Fill the pan roughly half full & use the rest for cupcakes.
For a 16-inch square cake pan, you typically need about 12 to 14 cups of cake batter. This amount ensures the batter fills the pan to a suitable level without overflowing during baking. It's important to leave some space for the cake to rise, so filling the pan about two-thirds full is ideal. Adjust the recipe as needed based on the specific ingredients and desired cake height.
How deep is the pan? 2" or 3"? It makes a huge difference.
The capacity of cake pans can vary based on their size and depth. Generally, a standard 9-inch round cake pan holds about 6 cups of batter, while a 6-inch round pan holds around 3 cups. For Wilton heart-shaped cake pans, the smaller 6-inch pan typically holds about 3 cups of batter, while the larger 9-inch heart pan can hold around 6 to 7 cups, depending on the specific model and depth. Always check the packaging or manufacturer's guidelines for precise measurements.