According to cookbook author Rose Levy Beranbaum, you can switch an 8-inch pan for a 9-inch pan when making brownies, pound cake, and dense fruit cakes. But when it comes to delicate cakes such as angel food cakes, it’s best to stick with the specified pan. Heavy batters may come up to 2/3 of a pans capacity while light batters should not exceed the midpoint of the pan. We recommend following recipe instructions. If you must switch pans, be sure to check out baking pan size conversion charts.