How long in a convection oven is equivalent to 40 minutes at 425 degrees in a conversion oven?

In a convection oven, you typically reduce the cooking time by about 20% and lower the temperature by 25°F. Therefore, for a recipe that calls for 40 minutes at 425°F in a conventional oven, you would set the convection oven to approximately 400°F and cook for about 32 minutes. Always check for doneness a few minutes before the adjusted time, as ovens can vary.