Gas mark 8 — all four oven scales
Gas marks are the scale on British and Irish gas ovens: gas mark 1 is 275°F / 140°C and each whole mark up adds 25°F. Gas mark 8 lands at 450°F / 230°C, which the traditional cookbook descriptors call a hot oven. If your recipe is older or British and your oven is not, these two numbers are the whole translation.
For a conventional recipe in a fan (convection) oven, use 210°C — the standard UK adjustment is conventional minus 20°C (a 36°F difference), because moving air transfers heat faster than still air; the oven isn't hotter than its dial, it just cooks faster at the same setting. Hoover also says long cooking times can be shortened by up to 10 minutes per cooking hour — check the food is cooked. Bake times are otherwise unaffected by converting between scales: 230°C and 450°F are the same setting.
Where gas mark 8 sits on the chart
| °F | °C | Fan °C | Gas mark | Descriptor |
|---|---|---|---|---|
| 375°F | 190°C | 170°C | 5 | Moderately hot |
| 400°F | 200°C | 180°C | 6 | Moderately hot |
| 425°F | 220°C | 200°C | 7 | Hot |
| 450°F | 230°C | 210°C | 8 | Hot |
| 475°F | 245°C | 225°C | 9 | Very hot |
See the full chart on the oven temperature converter → · Fan oven conversion chart →
What bakes at this temperature
450°F / 230°C is the territory of pizza and lean, crusty loaves. Home ovens cycle above and below their set point and many run hot or cold from the factory — a standalone oven thermometer on the middle rack tells you more than any conversion chart can.