Gas Mark Converter
Convert oven temperatures between gas mark, °C, °F and fan °C.
Results are provided as is, for general information. Check anything important before relying on it. See the Terms of Use.
About this tool
Gas mark is the UK oven-dial scale: a number from 1 to 9 that maps to a fixed pair of temperatures — gas 4 is 350 °F / 180 °C, gas 6 is 400 °F / 200 °C — with ¼ and ½ dial steps below 1 for slow warming and meringue work. The two printed columns are rounded approximations of each other rather than exact conversions (gas 3's 325 °F is really 338 °F next to its 170 °C), so this tool always answers with the values the standard chart prints, which is what recipes and oven manuals expect. Enter any one of gas mark, Celsius, Fahrenheit or a fan-assisted Celsius setting; temperatures between dial values snap to the nearest mark, and the fan column applies the standard rule that a fan oven runs about 20 °C cooler than the conventional setting for the same result. Everything is computed in your browser.
How it works
Gas mark 4 = 180 °C = 350 °F = 160 °C fan Fan °C = conventional °C − 20
Gas marks are a dial setting, not a formula, so conversion uses the standard oven chart: each mark is a printed temperature, and marks above 1 rise by about 14 °C (25 °F). Fan ovens circulate hot air and cook hotter, so subtract 20 °C from the conventional temperature.
| Question | Working | Answer |
|---|---|---|
| Gas mark 4 in Celsius and Fahrenheit | chart row for mark 4 | 180 °C / 350 °F (160 °C fan) |
| 180 °C as a gas mark | nearest chart row | Gas mark 4 |
| 350 °F as a gas mark | nearest chart row | Gas mark 4 (180 °C) |
When to use it
Questions
Why does 180 °C give gas 4 when 356 °F is 180 °C exactly converted?
Because the chart, not the formula, defines the scale. Gas 4's printed row is 350 °F / 180 °C — the °F and °C columns are each rounded to friendly numbers, so they are not exact conversions of each other. The tool matches your input against its own column (Celsius input against the C column, Fahrenheit against the F) and then shows the full chart row, keeping the answer consistent with every printed conversion table.
What happens if I type a temperature between two dial values?
You get the nearest gas mark, with a note saying so: 185 °C is 5 °C from gas 4 (180) and 15 °C from gas 5 (190), so it snaps to gas 4. A dead-even tie goes to the lower mark. The temperatures displayed stay anchored on the chart row rather than your raw input, so results stay comparable to the printed tables.
How does the fan setting work?
Fan-assisted ovens circulate hot air and effectively run about 20 °C hotter than a conventional oven at the same dial setting, so recipes give fan temperatures roughly 20 °C lower. The tool treats fan input as conventional °C minus 20: fan 160 °C is conventional 180 °C, which is gas 4. This -20 °C rule is the standard convention across UK oven charts; a few manufacturers differ, so trust your oven's manual if it says otherwise.
Why is there a gas mark 10 and fractions below 1?
The dial has more range than the famous 1–9. Mark 10 (500 °F / 260 °C) is a real setting used for pizza and rapid baking, and below 1 the scale steps in quarters: ¼ (225 °F / 110 °C) for warming and ½ (250 °F / 120 °C) for very slow cooking. The tool covers the full dial and snaps anything outside it to the nearest end.
Is gas mark used outside the UK?
Mostly in the UK and Ireland, plus some Commonwealth markets; North American ovens have no gas mark dial. US recipes speak pure Fahrenheit (350 °F, 400 °F) and European ones pure Celsius (180 °C, 200 °C), which is exactly why the converter shows all three scales at once — a gas-mark recipe converts cleanly into either.