Oven temperature converter
Choose the scale in your recipe, enter the temperature and see the other three, plus a name such as moderate or hot. Gas mark 1 is 275 °F and each mark adds 25 °F; the fan setting uses the common rule of thumb of 20 °C lower.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose which scale your recipe uses and enter the temperature or gas mark.
- Read the conventional °C and °F, the nearest gas mark, the fan oven temperature and the description.
Gas mark chart
| Gas mark |
°F |
°C |
Description |
| ¼ |
225 |
110 |
Very slow |
| ½ |
250 |
120 |
Very slow |
| 1 |
275 |
140 |
Slow |
| 2 |
300 |
150 |
Slow |
| 3 |
325 |
160 |
Moderately slow |
| 4 |
350 |
180 |
Moderate |
| 5 |
375 |
190 |
Moderately hot |
| 6 |
400 |
200 |
Moderately hot |
| 7 |
425 |
220 |
Hot |
| 8 |
450 |
230 |
Very hot |
| 9 |
475 |
240 |
Very hot |
How the numbers are found
- Celsius to Fahrenheit: °F = °C × 1.8 + 32; the reverse is (°F − 32) ÷ 1.8.
- A temperature is matched to the nearest gas mark by its Fahrenheit value; above about 487 °F it shows “above gas mark 9”.
- Fan oven = conventional − 20 °C is a rule of thumb, not a physical law.
Worked example
A recipe asks for 350 °F. That is (350 − 32) ÷ 1.8 = 176.7 °C, normally set as 180 °C, which is gas mark 4 or about 160 °C in a fan oven.
Tips
- Oven dials drift; an oven thermometer tells you the real temperature.
- Some sources round the Celsius values differently by 10 °C; the values here follow one common published chart.
Frequently asked questions
What temperature is gas mark 4?
Gas mark 4 is 350 °F, which recipes give as 180 °C (conventional) or about 160 °C for a fan oven. It is the standard moderate oven for baking cakes.
How do gas marks work?
Gas mark 1 is 275 °F (140 °C), and every mark adds 25 °F up to gas mark 9 at 475 °F (240 °C). The two lowest settings are gas mark ¼ at 225 °F and ½ at 250 °F.
Why is gas mark 1 shown as 140 °C when 275 °F is 135 °C?
Published gas mark tables round the Celsius value to the nearest 10 °C, and recipes use those figures. The tool shows the table value for a gas mark, and the exact conversion (°F − 32) ÷ 1.8 when you enter a temperature.
How much lower should I set a fan oven?
A common rule of thumb is 20 °C lower than the conventional temperature, for example 160 °C instead of 180 °C. Ovens vary, so follow the manual or recipe if it gives a fan temperature.