Gas Mark 1 in Fahrenheit and Celsius
Gas mark 1 is 275 °F (140 °C) — a slow oven. For a fan/convection oven, set about 120 °C (250 °F).
| Celsius (conventional) | 140 °C |
|---|---|
| Fahrenheit | 275 °F |
| Fan / convection | about 120 °C (250 °F) |
| Gas mark | 1 (slow) |
Why fan ovens are set 20 °C lower
A fan (convection) oven moves hot air across the food, transferring heat faster at the same temperature. The standard adjustment is minus 20 °C (about 25 °F) from the conventional temperature — or keep the temperature and shorten the time by roughly a quarter. Recipes written "180 °C fan" already include the reduction.
Full oven temperature chart
| °C | °F | Fan °C | Gas mark |
|---|---|---|---|
| 110 | 225 | 90 | ¼ (very slow) |
| 120 | 250 | 100 | ½ (very slow) |
| 140 | 275 | 120 | 1 (slow) |
| 150 | 300 | 130 | 2 (slow) |
| 160 | 325 | 140 | 3 (moderately slow) |
| 180 | 350 | 160 | 4 (moderate) |
| 190 | 375 | 170 | 5 (moderately hot) |
| 200 | 400 | 180 | 6 (moderately hot) |
| 220 | 425 | 200 | 7 (hot) |
| 230 | 450 | 210 | 8 (hot) |
| 240 | 475 | 220 | 9 (very hot) |
Interactive converter and the printable chart: oven temperature conversion
Data verified 2026-08-20 · Methodology