Oven temperatures
Every oven setting in gas marks, Celsius, Fahrenheit and the fan equivalent, plus what each one is for.
The chart
| Gas mark | Fahrenheit | Celsius | Fan / convection | |
|---|---|---|---|---|
| 1/4 | 225°F | 110°C | 90°C fan | Very cool |
| 1/2 | 250°F | 130°C | 110°C fan | Very cool |
| 1 | 275°F | 140°C | 120°C fan | Cool |
| 2 | 300°F | 150°C | 130°C fan | Cool |
| 3 | 325°F | 170°C | 150°C fan | Warm |
| 4 | 350°F | 180°C | 160°C fan | Moderate |
| 5 | 375°F | 190°C | 170°C fan | Moderately hot |
| 6 | 400°F | 200°C | 180°C fan | Moderately hot |
| 7 | 425°F | 220°C | 200°C fan | Hot |
| 8 | 450°F | 230°C | 210°C fan | Very hot |
| 9 | 475°F | 240°C | 220°C fan | Very hot |
The three scales, and why they disagree
An oven dial is marked in one of three ways and recipes are written in all of them. Gas marks are exactly defined — mark N is 250 + 25N degrees Fahrenheit, so mark 4 is exactly 350°F — but the Celsius figures printed alongside them are not the arithmetic conversion. 350°F is 176.7°C, and every recipe in the world calls it 180°C. The rounding is deliberate and universal: oven thermostats are not accurate to a degree, dials are marked in tens, and a rounded number that everyone agrees on is more useful than an exact one nobody can set.
The fourth number is the fan. A fan or convection oven cooks as though it were about 20°C hotter, because moving air carries heat to the food faster than still air does. A recipe written for a conventional oven at 180°C means 160°C in a fan oven — and a recipe that gives only one number, without saying which, is the single most common reason a cake comes out overdone.
Celsius settings
- 100°C — 80°C fan, gas mark 1/4
- 110°C — 90°C fan, gas mark 1/4
- 120°C — 100°C fan, gas mark 1/2
- 130°C — 110°C fan, gas mark 1/2
- 140°C — 120°C fan, gas mark 1
- 150°C — 130°C fan, gas mark 2
- 160°C — 140°C fan, gas mark 3
- 170°C — 150°C fan, gas mark 3
- 180°C — 160°C fan, gas mark 4
- 190°C — 170°C fan, gas mark 5
- 200°C — 180°C fan, gas mark 6
- 210°C — 190°C fan, gas mark 7
- 220°C — 200°C fan, gas mark 7
- 230°C — 210°C fan, gas mark 8
- 240°C — 220°C fan, gas mark 9
- 250°C — 230°C fan, gas mark 9
Fahrenheit settings
- 225°F — gas mark 1/4, 107°C exactly
- 250°F — gas mark 1/2, 121°C exactly
- 275°F — gas mark 1, 135°C exactly
- 300°F — gas mark 2, 149°C exactly
- 325°F — gas mark 3, 163°C exactly
- 350°F — gas mark 4, 177°C exactly
- 375°F — gas mark 5, 191°C exactly
- 400°F — gas mark 6, 204°C exactly
- 425°F — gas mark 7, 218°C exactly
- 450°F — gas mark 8, 232°C exactly
- 475°F — gas mark 9, 246°C exactly
- 500°F — gas mark 9, 260°C exactly
Gas marks
- Gas mark 1/4 — 110°C, 225°F
- Gas mark 1/2 — 130°C, 250°F
- Gas mark 1 — 140°C, 275°F
- Gas mark 2 — 150°C, 300°F
- Gas mark 3 — 170°C, 325°F
- Gas mark 4 — 180°C, 350°F
- Gas mark 5 — 190°C, 375°F
- Gas mark 6 — 200°C, 400°F
- Gas mark 7 — 220°C, 425°F
- Gas mark 8 — 230°C, 450°F
- Gas mark 9 — 240°C, 475°F
Fan ovens: subtract 20 °C, and why
A fan moves the hot air instead of waiting for it to circulate, so heat reaches the food faster at the same air temperature. The convention is to set a fan oven 20 °C lower than a conventional recipe asks — 180 °C conventional becomes 160 °C fan — and to expect it to finish a little sooner even then.
The adjustment is a rule of thumb rather than a conversion, and it is worth knowing which way it errs. Fan ovens brown more and dry more, because moving air carries moisture away from the surface. For a roast that is the point; for a custard or a delicate cake it is the reason many recipes say to turn the fan off rather than to drop the temperature.
Gas marks have no fan equivalent — a gas oven with a fan is uncommon outside commercial kitchens — which is why gas conversions in this section are given against conventional electric.
Gas marks are not evenly spaced at the bottom
From gas mark 1 upward each step is 25 °F, a tidy arithmetic ladder. Below 1 the marks go ½ and ¼, and those are not half and a quarter of anything: gas mark ½ is 250 °F and ¼ is 225 °F, so the step from ¼ to ½ to 1 is the same 25 °F as every other step. The fractions are names, not multipliers.
That matters when a recipe says "the lowest your oven will go". A domestic gas oven bottoms out around gas mark ¼, about 110 °C, which is warmer than the 80–90 °C that slow-drying and low-temperature work often want. An electric oven usually reaches lower.
The number on the dial is not the temperature inside
Domestic ovens are commonly out by 10–15 °C, and being out by 25 is not unusual in an older one. The thermostat also cycles: it heats past the set point, switches off, drifts down, and switches back on, so the air swings either side of the number by several degrees continuously.
A cheap oven thermometer settles it, and it is the single most useful thing to put in an oven that keeps producing results half a shade off. Once you know your oven runs 15 °C cool, every recipe in the world is corrected by the same 15 °C, and the conversions on these pages become exact rather than approximate.