Oven Temperature Converter
Your oven is probably not the temperature it claims.
Convert Oven Temperature. Your oven is probably not the temperature it claims. Shows the working, not just the answer.
Commonly 20 °C, though manufacturers differ
Conventional oven
180 °C
160 °C fan · 356 °F · gas mark 4
A fan oven moves hot air, so it cooks faster at the same dial setting — the conventional advice is to drop about 20 °C, and manufacturers differ enough that your own oven is the authority. Oven thermostats also drift: an oven thermometer costs very little and frequently reveals a discrepancy of 15 to 20 °C, which is more than the fan adjustment being argued about.
How the Oven Temperature Converter works
Celsius, Fahrenheit, gas mark and the fan-oven equivalent, with a note on what each range suits. The fan reduction is an input because manufacturers differ, and an oven thermometer beats all of it.
Also known as: what is gas mark 4 in celsius · fan oven conversion chart · fahrenheit to celsius for baking · oven temperature equivalents
Three scales that describe the same heat
Gas marks, Celsius and Fahrenheit all persist because different countries and different eras standardised on different scales. Gas mark 4 is 180 °C and 356 °F, and each gas mark step is 10 to 20 °C — a coarse scale by design, since a gas oven's control is coarse too.
The conversion between Celsius and Fahrenheit is exact. The conversion to gas marks is a lookup, because the marks were defined as positions on a valve rather than derived from a temperature, and the published equivalents are conventions rather than calculations.
This matters when a recipe gives one scale and the oven has another. Reading gas mark 6 as 200 °C is right; interpolating between marks is not really meaningful, because the underlying control does not resolve that finely.
The fan adjustment, and what it is compensating for
A fan oven circulates hot air rather than relying on convection, so heat transfers to the food faster at the same air temperature. The conventional response is to drop the setting by about 20 °C, and sometimes to shorten the time by around 10% as well.
Manufacturers differ enough that the figure is worth checking against your own oven's manual rather than treating 20 as universal. Some fan ovens are calibrated to display the conventional equivalent already, which means applying the adjustment twice.
The fan also evens out the oven, which is a separate benefit. Conventional ovens have pronounced hot and cool spots, and the difference between the top and bottom shelf can exceed the fan adjustment being debated — which is why shelf position matters more in a conventional oven.
Your oven is probably not the temperature it claims
Domestic oven thermostats commonly drift 15 to 20 °C from the dial, and some cycle by more than that between the element switching on and off. That is larger than the fan adjustment and larger than the difference between two gas marks.
An oven thermometer left on the shelf you actually cook on, for twenty minutes after the oven says it has preheated, settles it. It is inexpensive and it frequently explains a persistent problem that was blamed on a recipe.
Preheating is the related issue. The indicator responds to air temperature while the walls and shelves are still absorbing heat, so an extra ten to fifteen minutes makes a real difference to bread, pizza and pastry — anything that depends on thermal mass rather than air temperature alone.
Where to go next
The Oven Temperature Converter question rarely arrives on its own. These are the ones that usually come with it:
- Baking Conversion Calculator — A cup of honey outweighs a cup of flour nearly three to one.
- Cooking Time Calculator — Twice the weight is nowhere near twice the time.
- Turkey Cooking Time Calculator — The breast and the thigh finish at different times.
- Ring Size Calculator — Finger measurement to US, UK, EU and Japanese sizes.
Frequently asked questions
What is gas mark 4 in Celsius?
180 °C in a conventional oven, or 356 °F. In a fan oven the usual advice is to drop about 20 °C, giving 160 °C.
How much should I reduce for a fan oven?
Conventionally 20 °C, sometimes quoted as 25. A fan moves hot air across the food, so heat transfer is faster at the same air temperature. Manufacturers differ, which is why it is an input here.
Does the cooking time change with a fan oven?
Usually shortening by around 10% as well as dropping the temperature, though it varies with the dish. Check earlier than the recipe says the first time you use a new oven.
Is my oven accurate?
Frequently not. Thermostats commonly drift 15 to 20 °C from the dial, which is more than the fan adjustment being argued about. An oven thermometer costs very little and settles it.
Why do recipes give three different temperatures?
Because gas marks, Celsius and Fahrenheit all persist in different countries and older recipes. They describe the same heat, and gas marks are coarse — each step is 10 to 20 °C.
Where should I put the oven thermometer?
In the middle of the shelf you actually cook on. Ovens have hot and cool spots, and the difference between the top and bottom shelf can exceed the fan adjustment.
How do I check my oven's real temperature?
An oven thermometer on the shelf you cook on, left for twenty minutes after the oven says it has preheated. Thermostats commonly drift 15 to 20 °C, and some cycle by more than that.
Should I preheat for longer than the light suggests?
Usually. The indicator responds to air temperature, while the oven walls and shelves are still absorbing heat. Ten to fifteen extra minutes makes a real difference to bread and pastry.
Which shelf should I use?
The middle for most baking. Heat rises, so the top shelf browns faster and the bottom shelf is cooler — the difference can exceed the fan adjustment being debated.
Why does my cake brown before it cooks through?
The oven is running hot, the tin is too small so the batter is too deep, or both. Lowering the temperature and extending the time is the usual fix.
What is a combi or multifunction oven set to?
Read the mode rather than the dial. Fan-assisted, fan, conventional and grill all behave differently at the same setting, and the manual's temperature advice is mode-specific.
Does opening the door matter?
Yes, particularly for bread and soufflés. Each opening drops the air temperature sharply and it takes minutes to recover, which is why a door with a window earns its cost.
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