Three oven scales, one conversion
Recipes come in Celsius, Fahrenheit or the British Gas Mark scale, and switching between them mid-cook is a common source of mistakes. Celsius and Fahrenheit convert with a simple formula (°F = °C × 9/5 + 32), while Gas Mark is a stepped scale where each mark is a fixed temperature — Gas Mark 4 is about 180 °C / 350 °F, a typical "moderate" oven.
How Gas Mark works
Gas Mark runs from 1/4 (very low, ~110 °C) up to 9 (very hot, ~240 °C), rising roughly 14 °C per whole mark. Because it's not continuous, this tool snaps any temperature to the nearest mark when converting to Gas, and shows the exact °C and °F alongside so nothing is lost.
| Gas Mark | °C | Fan °C | °F |
|---|---|---|---|
| ¼ | 110 | 90 | 225 |
| ½ | 130 | 110 | 250 |
| 1 | 140 | 120 | 275 |
| 2 | 150 | 130 | 300 |
| 3 | 170 | 150 | 325 |
| 4 | 180 | 160 | 350 |
| 5 | 190 | 170 | 375 |
| 6 | 200 | 180 | 400 |
| 7 | 220 | 200 | 425 |
| 8 | 230 | 210 | 450 |
| 9 | 240 | 220 | 475 |
Fan-oven figures are the conventional temperature minus about 20 °C. Gas Mark and °F follow the standard UK oven chart; a live °C↔°F calculation can differ by a degree or two.
Fan vs. conventional ovens
A fan (convection) oven cooks hotter than a conventional one at the same dial setting, so recipes often say to drop the temperature by about 20 °C for fan. This converter handles the scale conversion; adjust for your oven type separately if the recipe specifies conventional and yours is fan.
Frequently asked questions
What is Gas Mark 4 in °C?
About 180 °C (350 °F), the classic "moderate oven" used for a huge range of baking and roasting.
Do I adjust for a fan oven?
Yes, separately from the scale conversion. As a rule of thumb, reduce a conventional temperature by about 20 °C for a fan oven — so 180 °C conventional becomes about 160 °C fan.
What is Gas Mark 5?
Gas Mark 5 is about 190 °C (375 °F) — a moderately hot oven, common for cakes and roast chicken. On a fan oven, set around 170 °C.
What is 180 °C in Fahrenheit and Gas Mark?
180 °C is 350 °F, which is Gas Mark 4 — the standard "moderate" oven. On a fan oven, use about 160 °C.
How do I convert Gas Mark to Fahrenheit?
For Gas Marks 1 to 9, multiply the mark by 25 and add 250: Gas Mark 6 = 6 × 25 + 250 = 400 °F. The chart above lists every mark.