Fahrenheit or Celsius? How Does Oven Temperature Conversion Work?

Clear Answer

To convert an oven temperature from Fahrenheit to Celsius, subtract 32, multiply by 5, then divide by 9, so 350°F works out to 176.7°C. Recipes round that to the nearest 10 degrees and print it as 180°C, which is also gas mark 4 on a UK cooker.

That rounding is what trips people up, so it helps to know what recipes print for every common setting from 250°F to 500°F.

What is the Fahrenheit to Celsius formula?

The Fahrenheit to Celsius formula is °C = (°F minus 32) x 5/9. Going the other way, °F = (°C x 9/5) plus 32. The 32 is there because water freezes at 32°F and 0°C, and the 5/9 is there because the Celsius degree is bigger: 100 Celsius degrees cover the same span as 180 Fahrenheit degrees between freezing and boiling.

Here is the math worked out for a common cookie temperature:

1. Start with 375°F.
2. Subtract 32 to get 343.
3. Multiply by 5 to get 1,715.
4. Divide by 9 to get 190.6°C.
5. Round to the nearest 10 for the oven dial: 190°C.

If you want a faster mental shortcut, halve the Fahrenheit number and subtract about 10 to 15. Half of 400 is 200, minus a bit lands you near 204°C, which recipes print as 200°C. The shortcut is rough at the low end, so use the full formula or the chart for anything under 300°F.

What is 350°F in Celsius?

350°F is 176.7°C. Almost every recipe, cookbook and oven dial rounds that to 180°C, and UK recipes call it gas mark 4. You will occasionally see 175°C or 177°C in recipes written by bakers who like precision, and those are fine too.

The 3 degree gap between 177°C and 180°C is smaller than the error in most home ovens. Which?, the UK consumer testing group, found that many ovens do not hold the temperature you set, and the least accurate models it tested ran as much as 40°C over. Rounding is not where your cake goes wrong.

Oven temperature conversion chart from 250°F to 500°F

This is the chart to keep on the fridge. The exact column shows the true math. The "recipes print" column shows how cookbooks and packaging round it, and the gas mark column follows the standard UK scale.

Gas marks and descriptions follow the conversion tables published by Which? and the gas mark entry on Wikipedia, which agree on every mark from 1 to 9. Gas mark 10 at 500°F appears only on some cookers. The 325°F row is the one place sources disagree: Which? prints 160°C and the Wikipedia table prints 170°C. The true value is 162.8°C, so 160°C is the closer pick, and that is the one we follow.

Notice that 275°F does not round down to 130°C even though the math says 135°C. Recipe writers usually round 135 up to 140°C to match gas mark 1, so you will see 140°C far more often.

How do you convert gas mark to Fahrenheit?

From gas mark 1 upward, each step adds 25°F, starting at 275°F. That gives you a quick gas mark to Fahrenheit rule: multiply the gas mark by 25, then add 250. Gas mark 4 is 4 x 25 + 250 = 350°F, and gas mark 7 is 425°F.

Below gas mark 1, the scale drops in fractions:

• Gas mark 1/4 is about 225°F (110°C)
• Gas mark 1/2 is about 250°F (120°C)
• Gas mark 1 is 275°F (140°C)

Those low settings show up in old British recipes for meringues, slow-dried fruit and rich fruitcakes. The scale started in the 1920s with the Regulo thermostat on gas cookers, and the name "gas mark" stuck long after the brand faded. Older handwritten recipes might say "Regulo 5," which means the same thing as gas mark 5, or 375°F.

What do recipe temperatures look like side by side?

Recipes from Europe, Australia and the UK rarely give Fahrenheit, so the useful skill is reading a Celsius number and knowing what it means. Most of them sit on a handful of familiar settings.

When you scale the amounts in a metric recipe, convert the temperature the same careful way you would convert cups to grams. A cake that bakes at 170°C in the original was tested at about 340°F. Set your dial to 340°F if it allows, or pick 325°F and add a few minutes rather than rushing it at 350°F.

How do you go from Celsius to Fahrenheit for baking?

Multiply by 9, divide by 5, then add 32. For 180°C that is 180 x 9 = 1,620, divided by 5 is 324, plus 32 is 356°F. Bakers treat that as 350°F, because recipes almost always round to the nearest 25°F mark that American recipes use.

For Celsius to Fahrenheit for baking, rounding to the nearest familiar setting works for most things. The exceptions are recipes that depend on a narrow window:

• Custards and cheesecakes. These can curdle or crack if they run hot, so round down when you are between two settings.
• Meringues and macarons. Low oven temperatures matter here, and a 10°F jump can brown the shells. Use the closest number your dial allows.
• Breads with a long bake. A slightly hotter oven darkens the crust before the inside is done. Round down and check with a thermometer.
• Cookies. These are forgiving on temperature but very sensitive to butter and flour, so if your batch keeps spreading flat in the oven, look there before blaming the conversion.

Weights get the same treatment when a European recipe lists ingredients by milliliter. A metric cup is 250 mL, a little bigger than a US cup, so the temperature is not the only thing that shifts.

What fan oven setting should you use for a Celsius recipe?

A fan oven setting for a Celsius recipe is usually 20°C lower than the regular temperature. That is the rule Which? gives, and it matches the fan column printed on UK oven charts: 180°C in a regular oven becomes 160°C fan. Many UK recipes now print both, such as "180°C, 160°C fan, gas mark 4."

Watch for recipes that only list one number. Which? notes that a recipe giving a single temperature is often written for a fan oven, so check the recipe notes or the author's other recipes before you assume.

American recipes say "convection" instead of "fan," and the usual adjustment there is 25°F lower or a shorter bake time. The details, like when to drop the temperature and when to shorten the time instead, are worth knowing before you bake with convection. Do not stack both adjustments on a recipe that already accounts for the fan.

Why does your oven still not match the number on the dial?

You can do a perfect conversion and still get pale cookies or a burnt crust, because the number on the dial is only a target. Ovens heat by cycling the element or burner on and off, so the air temperature swings above and below the set point the whole time it bakes.

A few things cause most of the drift:

1. The thermostat is off. Which? found ovens running 40°C hot at their worst, and some running cool. That is far bigger than any rounding.
2. Hot spots. The back corners and the area near the heating element often run hotter than the center rack.
3. Opening the door. Every peek dumps heat, and the oven needs time to recover.
4. Preheat beeps too early. Many ovens signal they are ready before the walls are fully hot. Give it another 10 to 15 minutes for baking.
5. Pan choice. Dark metal browns faster than light metal, and glass holds heat longer. Make sure your glass dish is oven safe at high temperatures before you use it at 220°C or higher.

The fix is an inexpensive oven thermometer on the center rack. Set the oven to 350°F, wait 20 minutes, and read it. If it says 375°F, turn your dial down 25 degrees for every recipe. The full method, including the sugar test and how to map hot spots, is worth running once if your bakes keep going wrong and you suspect your oven runs hot.

An instant read thermometer checks the food instead of the oven, which is the more reliable way to know a roast or a loaf of bread is done no matter what the dial says.

Does the conversion change what you cook?

Not as long as you round sensibly. Most savory food has a wide margin. A tray of bacon in the oven at 200°C or 400°F turns out the same, and roasted vegetables do not care whether you used 218°C or 220°C.

Baking has a narrower margin, and that is where it pays to be consistent. Pick one way of rounding, write it on the recipe card, and use the same setting every time so you can adjust bake time based on your own results. For more conversions you will need when a recipe comes from somewhere else, the measurements and conversions section has cups, grams and spoon measures in one place.

Seeing an oven thermometer against the dial

It helps to watch someone set an oven and then read an oven thermometer, because the gap between the dial and the real temperature is easier to believe once you see it.

Oven temperature comparison and convert C into F, F into C following formula.
By Bake Theory MB on YouTube. Their method may vary a little from ours. Watch on YouTube