Oven temperature conversion
Oven temperature conversion
Celsius to Fahrenheit to gas mark, with the fan oven equivalent for each. The fan setting is the one most recipes get wrong.
Fan ovens run about 20 °C hotter than the dial suggests, so a fan setting is always 20 °C below the conventional one.
More oven times
Common questions
Why subtract 20 °C for a fan oven?
A fan circulates the hot air instead of letting it stratify, so heat reaches the food far faster even though the air is the same temperature. The effect is roughly equivalent to 20 °C more in a conventional oven, so recipes written for conventional need 20 °C taken off. Some manufacturers say 25; 20 is the common convention and close enough for anything but delicate baking.
What is a gas mark in Celsius?
Gas mark 1 is 140 °C and each mark up adds roughly 14 °C, so mark 4 is 180 °C, mark 6 is 200 °C and mark 9 is 240 °C. Below mark 1 the scale goes to ½ and ¼ for very low settings, which is where meringues and long slow cooking live.
How do I convert Celsius to Fahrenheit myself?
Multiply by 9, divide by 5, add 32. In a kitchen, doubling and adding 30 gets you within a few degrees, which is inside the accuracy of most domestic ovens anyway.
Is my oven even accurate?
Probably not. Domestic ovens routinely run 10 to 20 °C off their dial, and they swing further as the thermostat cycles on and off. An oven thermometer costs very little and is the only way to know. If your baking is consistently pale or dark at the recommended setting, that is your answer.
Egg times come from the thermal-diffusion equation for a spherical egg published by Charles D. H. Williams (University of Exeter), calibrated so a large fridge-cold egg at sea level matches the times cooks actually use. Size, starting temperature and altitude then follow from the physics. Treat the result as a very good starting point, not a guarantee, because pans, hobs and eggs all vary.