Precise oven temperatures are important for ensuring that foods cook thoroughly and evenly. Most recipes suggest specific temperatures and cooking times for foods in order to provide cooks with some idea of how long the recipe should take, and imprecise temperatures can make the cooking time vary significantly.
Proper cooking temperature can be as important as proper pan selection when baking. In order to ensure that baked goods do not overbrown and roasted meats reach safe temperatures, ovens should operate as close as possible to the temperatures set by cooks. All ovens have some minor variance in temperature and cooking time, largely due to outside influences. Since many modern ovens cycle heat on and off to maintain temperature during the cooking time, most do not maintain an exact temperature at all times.
A precision oven thermometer works well to gauge the actual temperature of an oven. Cooks may place these inside the oven when baking or roasting foods to monitor how the temperature inside the oven relates to the setting chosen. A significant variance between temperatures may be a sign of heating element or thermostat problems that require replacement or repair. Oven thermometers range from under $5 for the most basic models to over $100 for the most expensive.