No matter your culinary skill level, this is a question many cooks are confused about. Basically, there is a short and a long answer. The simple solution: When in doubt, keep the oven rack adjusted to the middle position; this works fine for most cooking and baking situations. That said, certain situations benefit from varying the position. This is related to how ovens are engineered and how they source and distribute heat. Most have dual heating sources: one at the base of the oven and one at the top. Because hot air rises, the top of the oven tends to be consistently hotter. However, the lower heating element heats in bursts so it may swing hotter, then cooler as you cook. This is because (typically) both elements heat up when we preheat the oven, but once it has reached the desired temperature, the bottom source is the one that will periodically kick in to maintain the internal temperature. Here are some basic guidelines for when to mix it up.
Top
This position is ideal for using a broiler, as this heating element is situated at the top of the oven. Broil foods you want to char or crisp quickly, like garlic bread, casseroles, and anything covered in melted cheese. Just keep a close eye on them, because it’s very easy to burn foods when broiling. The top rack is also handy when you’re baking two sheets of cookies simultaneously; keep one sheet in the middle of the oven and the other at the top, then switch the sheets midway through cooking. (You may need to add a couple of extra minutes to the baking time to offset the crowded oven.)
Middle
The default position. It’s ideal for most foods since it situates the item in the middle of the oven, allowing the hot air to circulate evenly around the food, resulting in even cooking. Use this for a single tray of cookies, sheet-pan dinners, fish, brownies, banana bread, and so on.
Bottom
This position affords close proximity to the heat source that maintains heat as you cook, making it perfect for pizza or other flatbreads that require a short exposure to intense temperatures. It may lack the intensity of a wood-burning oven, but it comes closer than the middle rack. Don’t forget to move your pizza to the top rack for a quick broil before serving (your A+ cheese pull will thank you).
