How many cups of batter will a 9x13x3 Inch cake pan hold?

A 9x13x3 Inch cake pan can hold about 12 cups of batter. This is because the volume of a rectangular prism is equal to the length times the width times the height. In this case, the length is 9 inches, the width is 13 inches, and the height is 3 inches. So, the volume of the pan is 9 * 13 * 3 = 351 cubic inches. Since there are 16 cubic inches in a cup, the pan can hold 351 / 16 = 21.94 cups of batter. However, it is always best to err on the side of caution and use a little less batter than the pan can hold, so that the batter does not overflow when it is baking.