Work out fan oven temperature instantly with clear inputs, formula shown and shareable results.
A fan oven circulates air so it cooks as though it were about 20 C hotter, which is why recipes written for conventional ovens are reduced by 20 C for fan. Skipping the adjustment overcooks the outside of cakes and pastry by a noticeable margin, and the gas mark equivalent matters for older recipe books.
Fan adjustment
fan temperature = conventional temperature - 20 C
Fahrenheit
F = C x 9 / 5 + 32
fan temperature = conventional temperature - 20 C. A fan oven circulates air so it cooks as though it were about 20 C hotter, which is why recipes written for conventional ovens are reduced by 20 C for fan.
Skipping the adjustment overcooks the outside of cakes and pastry by a noticeable margin, and the gas mark equivalent matters for older recipe books.
Enter temperature given in the recipe, convert. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.