Convection ovens require lower temperatures and shorter cooking times than regular ovens. The formula is easy to remember: Just remember the number 25. Generally, convection ovens can be set 25 degrees Fahrenheit lower and require 25 percent less baking time. Unfortunately, the reverse formula is not as easy to remember. When converting a recipe meant for a convection oven to use in a regular oven, add 25 degrees Fahrenheit and 33 percent more time.
Carefully read the recipe meant to be cooked in a convection oven and, if needed, write down or circle two numbers: the temperature and the amount of time required.
Add 25 degrees Fahrenheit to the temperature. Set your regular oven to that temperature.
Divide the number of minutes required for the convection oven by 3, then add the result to the time originally called for. (For example, if a recipe for a convection oven calls for 30 minutes, divide 30 by 3 to get 10, then add 10 minutes to the original 30 to get 40 minutes. Round numbers down to be safe.)