How oven temperature conversion works
Fahrenheit and Celsius convert to each other with one exact formula, no rounding involved. Gas mark is different: it is not a temperature scale at all, just a numbered dial from old gas ovens, and each mark is paired with a standard, slightly rounded Fahrenheit and Celsius figure by convention, not by the precise math formula. Enter a temperature in any one of the three and this converter gives you the other two: the exact conversion where one applies, and the standard baking convention where it applies, clearly labeled as which is which.
The formula
Here F is degrees Fahrenheit and C is degrees Celsius. This is the exact conversion, the same one used for weather or body temperature. Gas mark has no formula of its own: it is looked up from the standard table below instead.
Worked example
350 F, exact conversion: (350 - 32) × 5⁄9 = 318 × 5⁄9 = 176.7 C.
350 F, baking convention: recipes and oven dials round this to 180 C, which is gas mark 4, the standard pairing on every conversion chart, even though 176.7 C is the mathematically precise answer.
Gas mark 6, looked up: the standard table pairs gas mark 6 with 400 F and 200 C.
Fan adjustment for 200 C: 200 - 20 = 180 C fan, the widely used rule of thumb for a fan or convection oven.
The gas mark table
| Gas mark | Fahrenheit | Celsius | Description |
|---|---|---|---|
| 1 | 275 F | 140 C | Very low |
| 2 | 300 F | 150 C | Low |
| 3 | 325 F | 165 C | Low to moderate |
| 4 | 350 F | 180 C | Moderate (the most common baking temperature) |
| 5 | 375 F | 190 C | Moderately hot |
| 6 | 400 F | 200 C | Hot |
| 7 | 425 F | 220 C | Hot |
| 8 | 450 F | 230 C | Very hot |
| 9 | 475 F | 240 C | Very hot |
These pairings are the standard convention used on oven dials and in recipe books across the UK and Europe. They are rounded to friendly numbers, not derived from the exact F-to-C formula: gas mark 4's true conversion of 350 F is 176.7 C, but 180 C is what actually appears on the dial and in the recipe, so that is the number worth remembering.
Common baking temperatures, at a glance
| Fahrenheit | Celsius (convention) | Gas mark |
|---|---|---|
| 325 F | 165 C | 3 |
| 350 F | 180 C | 4 |
| 375 F | 190 C | 5 |
| 400 F | 200 C | 6 |
| 425 F | 220 C | 7 |
Why 350 F shows up in so many recipes
Maillard browning, the chemical reaction that turns a crust golden and gives baked goods their flavor and color, gets going in earnest somewhere between about 300 F and 350 F. That range is hot enough to brown the surface at a reasonable pace but not so hot that the outside burns before the inside finishes cooking, which is exactly the balance most cakes, cookies, and roasts need. It is a wide, forgiving zone rather than one precise number, which is a large part of why 350 F became the default oven setting for so many recipes rather than a coincidence of rounding.
Fan and convection ovens
A fan or convection oven moves air around the food, which transfers heat faster and more evenly than a still, conventional oven at the same temperature setting. The common fix is to lower a conventional recipe's temperature by about 20 C (roughly 25 F) when baking with the fan on, or to leave the temperature alone and cut the cooking time by about 25 percent instead. Both are rules of thumb, not physics: fan strength, oven size, and calibration all vary, so treat the fan-adjusted number as a starting point and check for doneness a little early the first time you try a recipe in a fan oven. An inexpensive oven thermometer on the middle rack is the most honest way to find out what your oven is actually doing, since dial and display readings can drift over years of use.
Converting the rest of a recipe
If a recipe's temperatures are the only unfamiliar part, this page is all you need. For everyday temperatures outside the kitchen, weather, body temperature, and the rest, the general temperature converter covers Fahrenheit, Celsius, and Kelvin. If the same recipe also hands you ingredients in cups, the cups to grams converter weighs them out by ingredient, and if you are resizing the whole recipe to a different serving count, the recipe scaler rounds every ingredient to a measurement you can actually read off a cup or spoon.