Fan Oven Adjustment Calculator

A fan oven (convection oven) has a fan that circulates hot air around the food. This creates a more even temperature throughout the oven and means food cooks faster and more evenly. The moving air effectively increases the cooking temperature by about 20°C.

The 20°C rule is a reliable guideline used in the UK. Some sources suggest 15-25°C depending on the oven. If your fan oven runs particularly hot or cool, adjust accordingly. An oven thermometer helps you fine-tune.

Fan ovens typically cook about 10% faster due to the efficient heat distribution. For short bakes (under 20 minutes), the difference is minimal. For longer bakes, reducing time by 10% is a good starting point — but always check for doneness.

Most modern UK ovens are fan ovens or multifunction ovens that offer both settings. Older recipes and many cookbooks use conventional temperatures. If your oven has a fan symbol, use the fan temperature (lower number).

The standard advice is to reduce by 20 degrees C for fan ovens, and this works for most ovens. However, some modern fan ovens are already calibrated to account for this, so check your oven manual. If your bakes consistently brown too quickly, your fan oven may run hot and you should reduce by 25 degrees C instead.