Oven Temperature Converter

This oven temperature converter turns the Fahrenheit figures and British gas marks found in recipes into the Celsius numbers on your oven dial, and the other way around. It is meant for moments like reading "bake at 350°F for 30 minutes" with a Celsius oven, or meeting a UK recipe that says "gas mark 4". Below you will find the formulas, where gas marks come from, how to adjust for a fan oven, and why your oven's own error can matter more than the conversion.

What is a gas mark?

Gas mark is the numbered scale on the dial of many British, Irish and Commonwealth gas ovens. The numbers rise from 1 to 9, with ¼ and ½ below 1; the higher the number, the hotter the oven. Early gas ovens had no temperature scale, only a flame setting, so manufacturers published a chart of what each setting roughly produced and the numbers stuck. That makes gas mark a conventional scale rather than a physical unit, and the lowest settings (¼ and ½) are listed with slightly different temperatures in different sources. The table on this page uses the widely quoted correspondences. If your oven's manual has its own chart, that one comes first.

Many current British recipes give all three numbers together, for example "180°C / 160°C fan / gas mark 4". When you see that format, simply pick the number that matches the kind of oven you own.

The conversion formulas

• Celsius to Fahrenheit: °F = °C × 9 ÷ 5 + 32
• Fahrenheit to Celsius: °C = (°F − 32) × 5 ÷ 9
• Gas mark has no formula. The tool looks up the nearest setting in the table above.

For example, 180°C becomes 180 × 9 ÷ 5 + 32 = 356°F. In the other direction, 350°F is (350 − 32) × 5 ÷ 9 = 176.7°C, not exactly 180°C. Recipes still equate 350°F with 180°C because home oven dials move in steps of 5 or 10 degrees and the oven's real temperature usually wobbles by more than that anyway. The tool shows rounded values in the boxes but prints the exact arithmetic, with one decimal, in the "Arithmetic" chip.

Celsius to Fahrenheit, gas mark and fan oven table

The values below are computed from the formulas when the page is built. The fan column applies the common rule of thumb of lowering the setting by 20°C, and the "25°F dial" column is the nearest 25°F step, since many American ovens and recipes move in 25-degree increments.

Fahrenheit to Celsius table (for American recipes)

American recipes usually move in 25°F steps. Each row lists the exact Celsius value and the figure rounded to the nearest 5°C for a Celsius dial.

Worked examples

• A 350°F cookie recipe: exactly 176.7°C, so set a Celsius oven to 175°C or 180°C. The nearest gas mark is 4 (180°C).
• A British pie at gas mark 6: the table gives 200°C (400°F). In a fan oven, start around 180°C and watch the color.
• 425°F for pizza or roast vegetables: (425 − 32) × 5 ÷ 9 = 218.3°C, so about 220°C. Many home ovens top out near 230°C, so check your maximum before preheating.
• A recipe that says 160°C fan, for a conventional oven: conventional ovens are commonly set about 20°C higher than fan ovens, so use 180°C. The tool's fan setting only subtracts 20°C, so for this direction add the 20°C by hand.

Why fan (convection) ovens need an adjustment

A fan oven moves hot air around constantly, which delivers heat to the surface of the food faster. At the same dial setting the outside cooks and browns sooner than in a conventional oven, so British recipes often say to reduce the temperature by about 20°C (roughly 25°F) when using a fan. The tool assumes the recipe was written for a conventional oven and, when you pick "Fan oven", subtracts 20°C. Manufacturers' guidance ranges from about 10 to 20°C, so the first time you bake a recipe, begin checking at around 80 percent of the stated time. Air fryers and compact convection ovens are fan-driven too, but their small interior and strong airflow mean the right reduction varies from model to model, and no single rule fits them all. Follow the appliance manual and your own first-bake notes.

Common mistakes and limits

• The dial is not the real temperature. Home ovens are often off by 10 to 30 degrees. A perfect conversion cannot fix an inaccurate oven; an inexpensive oven thermometer placed on the middle rack is worth the few minutes it takes to check.
• Skipping the preheat. Recipe temperatures assume a fully preheated oven. Even after the beep, giving the walls another 5 to 10 minutes to soak up heat often helps.
• Reading a number without its unit. 350 means 350°F in the US and would be far beyond the limit of a Celsius oven. Always check for °F or °C.
• Interpreting the lowest gas marks. Sources list ¼ and ½ anywhere between roughly 110 and 130°C, so for meringues and slow drying verify with a thermometer.
• Oven temperature is not food safety. The setting of the oven and the internal temperature a food must reach are separate things, and safe internal temperatures differ by country, by food and by authority. Use a food thermometer and the official guidance for your region instead of any figure on this page.

Putting the result to use

Round the converted temperature to the nearest step your dial allows, usually 5 or 10 degrees. For high-heat recipes, make sure the number does not exceed your oven's maximum. With a fan oven, begin with the adjusted figure and check the color at about three quarters of the recipe time. The first time you try a recipe, treat the first tray as a test and write down the setting that worked in your oven; next time you will not need the converter at all.

Other kitchen conversions

For cups, spoons and ounces, use the Cooking Measurement Converter, which also compares cup sizes by country. For general length, weight and volume, the Unit Convertercovers the rest.

Frequently Asked Questions