How much cake batter for a 12x12x3 cake pan?

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.