How to use the oven temperature converter
- Pick the scale you have in Convert from: Fahrenheit (°F), Celsius (°C) or Gas mark.
- Type the number in Temperature, for example 350. If you chose Gas mark, the box becomes a Gas mark list from 1/4 to 9.
- Read the sentence in the blue box, then the table under it. The first row is for a conventional oven and the second is the lower setting for a fan (convection) oven.
- Check the chart at the bottom. When your temperature matches a gas mark, that row is highlighted.
How the conversion works
Fahrenheit and Celsius use the standard formulas, °C = (°F - 32) × 5 ÷ 9 and °F = °C × 9 ÷ 5 + 32, given in the NIST Guide to the SI, Appendix B.8. Gas mark is a printed scale of fixed settings: mark 1 is 275 °F, each whole mark adds 25 °F up to mark 9 at 475 °F, and 1/4 and 1/2 are 225 °F and 250 °F. Charts such as the Which? table and Wikipedia's gas mark article round the Celsius column, so gas mark 4 is listed as 180 °C although 350 °F is exactly 176.7 °C.
A fan oven cooks faster, so Which? says its temperatures are typically around 20 °C lower, and America's Test Kitchen reports that manufacturers advise 25 to 50 °F lower. The tool lowers by 25 °F when you enter °F and by 20 °C when you enter °C or a gas mark.
Worked example with the default 350 °F
For 350 °F the tool works out (350 - 32) × 5 ÷ 9 = 176.7, shown as 177 °C. That is within 5 degrees of the gas mark 4 setting, so the result reads: "350 °F is 177 °C or gas mark 4 in a conventional oven. For a fan oven, set 325 °F (163 °C)." The fan figure is 350 - 25 = 325 °F, which is 162.8, shown as 163 °C. The chart row for gas mark 4 lists 350 °F, 180 °C and 160 °C fan because recipes round to dial steps.
Limits and edge cases
- The tool accepts 100 to 1000 °F and 40 to 540 °C. A comma counts as a decimal point.
- A temperature more than 5 degrees from every chart value is reported as between two gas marks, naming the closer one. Below 1/4 or above 9 the tool says so.
- Which? lists gas mark 3 as 160 °C and Wikipedia as 170 °C. The tool uses 160 °C and mentions the other.
- Gas ovens have no fan setting, so the gas mark cell of the fan row reads "Not used".
- Which? notes that a recipe with a single temperature is usually written for fan ovens, so read the recipe before lowering anything. Cooking times do not convert.
Baking with a swap? Try the baking substitutions finder. Once the oven is hot, the cooking timer keeps time. For other units, see the temperature converter.
Oven temperature FAQ
What is 350 °F in Celsius?
350 °F is 176.7 °C, which the tool shows as 177 °C. Recipes usually round it to 180 °C, which is gas mark 4.
What gas mark is 200 °C?
200 °C is gas mark 6, which is 392 °F exactly and 400 °F on the chart. For a fan oven, set 180 °C.
How do I convert an oven temperature for a fan oven?
Lower it by about 20 °C or 25 °F. For example, 180 °C becomes 160 °C and 350 °F becomes 325 °F. Start checking the food a few minutes early.
Is 180 °C the same as 350 °F?
Almost. 180 °C is exactly 356 °F, a 6 degree difference that recipes ignore. Both are gas mark 4.
What is gas mark 4 in Fahrenheit?
Gas mark 4 is 350 °F, or 180 °C on the usual chart.
Sources: NIST, Which?, Wikipedia, America's Test Kitchen.