Why is a fan oven different from a conventional oven?

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.

Is it always exactly 20°C difference?

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.

Should I also adjust the baking time?

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.

Are most modern ovens fan or conventional?

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).

Do all fan ovens need the same temperature reduction?

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.

BakeCalcs

Fan Oven Adjustment Calculator

Calculate the correct fan oven temperature from a conventional oven recipe, or vice versa.

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Conventional Temperature

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How We Calculate This

Fan ovens circulate hot air, making them about 20°C more effective than conventional ovens at the same dial setting. This calculator applies the standard UK adjustment.

The Rule

Conventional to fan: Subtract 20°C
Fan to conventional: Add 20°C
Time adjustment: Fan ovens cook ~10% faster

Common Conversions

160°C conventional = 140°C fan (cakes, biscuits)
180°C conventional = 160°C fan (standard baking)
200°C conventional = 180°C fan (bread, pastry)
220°C conventional = 200°C fan (high-heat roasting)

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Last updated: February 2026

All calculations are based on standard ratios and conversions. Results may vary with specific ingredients, equipment, and conditions.