While the difference in sizes seems small, it actually equals a 15% difference in capacity. That can really affect the outcome of your bake—especially in quick breads and those that use less than three cups of flour. If your recipe calls for a 8½x4½-inch pan and you use a 9×5, your bread could fall flat instead of properly rising.

Loaf Pans 8×4 inch loaf pan holds 4 cups of batter, the same as a 6×2 inch round pan. 9×5 inch loaf pan holds 8 cups of batter, the same as a 9×2 inch round pan and an 8×2 inch square pan.