140°C — all four oven scales
The exact conversion is °C × 9/5 + 32, so 140°C works out to 284°F. Recipe writers don't use the exact figure: the long-standing pairing puts 140°C alongside 275°F and gas mark 1, and published conversion charts (Which?'s among them) treat the paired values as the same setting. Follow whichever scale your dial shows.
For a conventional recipe in a fan (convection) oven, use 120°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: 140°C and 275°F are the same setting.
Where 140°C sits on the chart
| °F | °C | Fan °C | Gas mark | Descriptor |
|---|---|---|---|---|
| 225°F | 110°C | 90°C | ¼ | Very slow |
| 250°F | 120°C | 100°C | ½ | Very slow |
| 275°F | 140°C | 120°C | 1 | Slow |
| 300°F | 150°C | 130°C | 2 | Slow |
| 325°F | 160°C | 140°C | 3 | Moderately slow |
See the full chart on the oven temperature converter → · Fan oven conversion chart →
What bakes at this temperature
275°F / 140°C is the territory of rich fruit cakes and other long, slow bakes. 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.