Oven Temperature Conversion: °C to °F, Fan Oven and Gas Mark

The short answer

To convert an oven temperature from Celsius to Fahrenheit, multiply by 9/5 and add 32; to go back, subtract 32 and multiply by 5/9. So 180°C is exactly 356°F, which recipes round to 350°F. If your oven has a fan, lower a conventional recipe temperature by about 20°C. You can check any exact value with the Temperature Converter.

The tricky part is not the arithmetic. It is knowing whether a recipe means a conventional or a fan oven, and how much rounding is normal.

Oven temperature chart

The rounded values below are the ones you will see in cookbooks and on oven dials. They come from the conversion table published by the UK consumer group Which?. The last column shows the exact Fahrenheit value of the Celsius figure, so you can see how much rounding is involved.

Gas mark	Conventional °C	Fan °C	Recipe °F	Exact °F of the °C value
1	140	120	275	284
2	150	130	300	302
3	160	140	325	320
4	180	160	350	356
5	190	170	375	374
6	200	180	400	392
7	220	200	425	428
8	230	210	450	446
9	240	220	475	464

Two things stand out. First, the rounded pairs are within about 10°F of the exact value. Second, the gap is not always in the same direction: gas mark 1 is listed as 275°F, but 140°C is really 284°F. Ovens themselves are rarely accurate to within a few degrees, so this level of rounding is normal and safe for everyday cooking.

Converting a US recipe for a Celsius oven

American recipes give temperatures in Fahrenheit for a conventional oven unless they say otherwise.

Open the Temperature Converter.

Type the Fahrenheit value, for example 350.

Set From to Fahrenheit (°F) and the result box to Celsius (°C). The exact value appears straight away: 176.666667.

Round to the nearest step on your oven dial. Most Celsius dials move in 10° or 20° steps, so 176.7°C becomes 180°C.

If your oven is a fan oven, subtract about 20°C. 180°C becomes 160°C.

Common US recipe temperatures and their exact Celsius values:

Recipe °F	Exact °C	Conventional dial	Fan oven
300	148.9	150	130
325	162.8	160	140 to 145
350	176.7	180	160
375	190.6	190	170
400	204.4	200	180
425	218.3	220	200
450	232.2	230	210

The converter's table under the result also shows the value in kelvin. You can ignore that row for cooking.

Converting a Celsius recipe for a Fahrenheit oven

Recipes from the UK, Europe, Australia and India usually give Celsius, and many already assume a fan oven.

Check the recipe for the words "fan", "fan-forced" or "conventional". If it gives two numbers, such as "200°C (180°C fan)", use the one that matches your oven.

Enter the Celsius value in the converter with From set to Celsius.

Round the result to the nearest 25°F, which is how most US oven dials and recipes work. 200°C is 392°F, so set 400°F.

If you have a US oven with a convection setting and the recipe gives a fan temperature, convert the fan figure directly. If you plan to use the regular bake setting, convert the conventional figure instead.

Fan oven or conventional: how much to adjust

A fan (convection) oven blows hot air around the food, so it heats more evenly and usually cooks faster. Which? says fan oven temperatures are typically around 20°C lower than conventional ones, and warns that if you do not lower the temperature the outside of the food can cook too fast. It also points out that most ovens sold today are fan-assisted, so a recipe that gives only one Celsius temperature may already assume a fan oven.

A practical approach:

• Recipe gives conventional temperature, you have a fan oven: lower by 20°C (a 20°C difference is 36°F, so about 35°F on a Fahrenheit dial) and check the food 5 to 10 minutes early.
• Recipe gives a fan temperature, you have a conventional oven: raise by 20°C.
• Recipe does not say: look at the cooking time and the colour. If a cake browns on top while the middle is raw, the oven was too hot for that recipe.

Your oven's manual is the best guide for its own fan settings, because some models already compensate automatically.

Quick mental conversion

When you only need a rough figure, for example while reading a recipe on your phone:

• °F to °C: subtract 30, then halve. 350°F becomes (350 − 30) ÷ 2 = 160°C. The exact answer is 176.7°C, so this shortcut underestimates at oven temperatures.
• °C to °F: double, then add 30. 180°C becomes 390°F. The exact answer is 356°F, so this overestimates.

These shortcuts work reasonably for weather temperatures but at oven heat they are off by roughly 15°C to 20°C, or about 35°F. For baking, use the exact formula or the chart above. The general Celsius to Fahrenheit guide covers the formula and everyday reference points in more detail.

Common mistakes

• Converting a fan temperature and then lowering it again. If the recipe already says "160°C fan", do not subtract another 20°C.
• Treating 356°F and 350°F as different settings. They are the same recipe instruction. The difference is rounding, not a different temperature.
• Using gas marks with an electric oven without converting. Gas mark 4 is 180°C conventional or 160°C fan, not 4 on an electric dial numbered 1 to 9.
• Forgetting the volume units. A US recipe that uses Fahrenheit probably uses cups and tablespoons too. The guide to cups, tablespoons and ml covers those conversions.

If your food still burns or stays raw

The conversion might be correct and the oven still wrong. Oven thermostats can run hot or cold. An inexpensive oven thermometer placed on the middle shelf shows the real temperature after preheating. If the thermometer reads 20°C higher than the dial, set the dial 20°C lower for every recipe.

Also give the oven time to preheat fully. Many ovens switch off the preheat light before the whole cavity has reached temperature, especially with a heavy baking stone or cast-iron dish inside.

Summary

• Exact formula: °F = °C × 9/5 + 32, and °C = (°F − 32) × 5/9.
• Recipe values are rounded: 180°C is printed as 350°F.
• Fan ovens: about 20°C lower than conventional.
• Gas mark 4 is the usual "moderate" setting: 180°C, 160°C fan, 350°F.

Use the converter for the exact figure, then round to your oven's dial.