How to check if your oven’s temperature is accurate
An oven thermometer is the most reliable way to find out if your oven’s temperature matches its settings or if it’s not baking properly. To test its temperature, center an oven rack then hang an oven thermometer from the middle-front of the rack. Preheat the oven to 350℉ and wait for your oven to signal that preheating is finished.
Most oven thermometers hang vertically from the upper rack so you can simply peek through the glass for an accurate reading. If you can’t see clearly, open the door quickly to get a reading and determine if your oven is under or overheating.