Gas Mark 3 — 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 3 lands at 325°F / 160°C, which the traditional cookbook descriptors call a moderately slow oven. If your recipe is older or British and your oven is not, these two numbers are the whole translation.
In a fan (convection) oven, use 140°C — the standard adjustment is conventional minus 20°C, because moving air transfers heat faster than still air. Make the temperature adjustment or shorten the bake time by about a quarter, never both. Bake times are otherwise unaffected by converting between scales: 160°C and 325°F are the same heat wearing different units.
Where gas mark 3 sits on the chart
| °F | °C | Fan °C | Gas mark | Descriptor |
|---|---|---|---|---|
| 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 |
| 350°F | 180°C | 160°C | 4 | Moderate |
| 375°F | 190°C | 170°C | 5 | Moderately hot |
See the full chart on the oven temperature converter →
What bakes at this temperature
325°F / 160°C is the territory of cheesecakes, shortbread and gentle sponges. Remember that most home ovens swing ±25°F around their set point and many run permanently hot or cold — a standalone oven thermometer on the middle rack tells you more than any conversion chart can.