Convert oven temperature between conventional (top/bottom heat) and convection (fan), so you hit the right temperature no matter what the recipe uses.
A convection oven circulates the air with a fan, so heat distributes more evenly and faster around the food than with traditional top/bottom heat. That's why you can usually set the temperature 15–25 °C lower with convection and still get the same result:
The calculator uses 20 °C as the main figure, and also shows a recommended range of 5 degrees around it. The exact difference varies somewhat between oven models and brands, so use the range as a general guide.
The convection fan circulates the hot air around the food, so heat transfers faster and more evenly than with conventional top/bottom heat alone. That's why you typically need 15–25 °C less to achieve the same baking or roasting result.
No, 20 °C is a common rule of thumb, but the actual difference can vary between oven brands and models. Check your oven's manual, or test it out the first time you use it.
The baking time is often a bit shorter with convection due to more even heat distribution, but it varies by dish. Keep an eye on it and use a toothpick test or food thermometer rather than relying blindly on the time in the recipe.