Why does my oven cook unevenly?

Nearly every oven has hot and cool areas, and the size of the difference is what separates normal from faulty. Before assuming a fault, it is worth establishing how far off it actually is.

An inexpensive oven thermometer placed in the centre answers this directly. Ovens commonly run twenty degrees or more from their setting, and the built-in sensor reports its own location rather than the average. Once you know your oven runs hot or cool, adjusting the dial compensates, and many ovens have a calibration offset in their settings for exactly this.

Airflow explains most unevenness within a single oven. Overcrowded shelves, oversized trays and foil laid across a shelf all block circulation and produce a cool region behind them. Leaving space around trays for air to move usually improves results more than any adjustment to temperature.

Rack position matters because heat rises and the elements are at specific positions. The middle rack is the most even in most ovens; the top browns faster and the bottom is closer to the base element.

Door seal condition is a genuine cause that is easy to check. Run a hand around the closed door for escaping heat, or check whether the seal has hardened or torn. A poor seal produces a permanent cool zone near the leak and lengthens cooking times generally.

Frequent door opening costs more heat than people assume, since the recovery takes minutes.

If the oven is convection capable, using the fan evens distribution considerably, though it also cooks faster, so recipes typically need around twenty degrees less than a conventional setting.