Quick answer: Gas mark 4 is 180°C, gas mark 6 is 200°C and gas mark 9 is 240°C in a conventional oven. Each step from gas mark 1 (140°C) upwards adds 25°F, roughly 10 to 20°C after rounding. For a fan oven, set about 20°C lower: gas mark 4 becomes 160°C fan. The full chart is below.
Gas marks come from the numbered thermostat dials on British gas cookers, and plenty of recipes still use them. If your oven is electric, you need the Celsius figure, and if it has a fan, you need to drop it a little further. For spoons, cups and other kitchen conversions, see our UK cooking measurements guide.
Gas mark to Celsius chart
Gas marks run from ¼ (110°C) to 9 (240°C). The table gives the usual UK conversions for a conventional (top and bottom heat) oven, the fan-oven equivalent, Fahrenheit, and the descriptive terms older recipes use.
| Gas mark | Conventional °C | Fan °C | °F | Description |
|---|---|---|---|---|
| ¼ | 110°C | 90°C | 225°F | Very cool |
| ½ | 120–130°C | 100–110°C | 250°F | Very cool |
| 1 | 140°C | 120°C | 275°F | Cool |
| 2 | 150°C | 130°C | 300°F | Cool |
| 3 | 170°C | 150°C | 325°F | Moderate |
| 4 | 180°C | 160°C | 350°F | Moderate |
| 5 | 190°C | 170°C | 375°F | Moderately hot |
| 6 | 200°C | 180°C | 400°F | Moderately hot |
| 7 | 220°C | 200°C | 425°F | Hot |
| 8 | 230°C | 210°C | 450°F | Hot |
| 9 | 240°C | 220°C | 475°F | Very hot |
Look up a gas mark
Choose a gas mark to see the matching conventional, fan and Fahrenheit settings.
Gas mark lookup
=How do gas marks relate to Fahrenheit?
From gas mark 1 upwards, each mark is 25°F hotter than the one before, starting at 275°F. That gives a simple formula: °F = 250 + (25 × gas mark). Gas mark 4 is 250 + 100 = 350°F, and gas mark 7 is 250 + 175 = 425°F. Below gas mark 1 the pattern changes: ½ is 250°F and ¼ is 225°F.
Gas mark thermostats were first fitted as standard to British gas ovens in the 1920s, when Britain still measured oven temperatures in Fahrenheit, so the scale steps in Fahrenheit rather than Celsius. You can check any Fahrenheit figure with the Fahrenheit to Celsius converter.
Why do some charts say gas mark 3 is 160°C?
Because 325°F is 162.8°C, which sits between two round numbers. UK charts round each mark to a tidy Celsius figure, and some round gas mark 3 down to 160°C while others use 170°C. The exact conversions show where the rounding happens:
| Gas mark | °F | Exact °C | Usual chart °C |
|---|---|---|---|
| ¼ | 225 | 107.2 | 110 |
| ½ | 250 | 121.1 | 120–130 |
| 1 | 275 | 135.0 | 140 |
| 2 | 300 | 148.9 | 150 |
| 3 | 325 | 162.8 | 160–170 |
| 4 | 350 | 176.7 | 180 |
| 5 | 375 | 190.6 | 190 |
| 6 | 400 | 204.4 | 200 |
| 7 | 425 | 218.3 | 220 |
| 8 | 450 | 232.2 | 230 |
| 9 | 475 | 246.1 | 240 |
A difference of 10°C rarely spoils a dish, but for delicate bakes it is worth testing your own oven, as the next section explains.
How do you convert gas mark for a fan oven?
Take the conventional Celsius figure and subtract about 20°C. A fan spreads heat more evenly, so food cooks at a lower setting. Gas mark 4 (180°C) becomes about 160°C fan, and gas mark 6 (200°C) becomes about 180°C fan. Many modern recipes print the fan figure as well, so check before reducing it twice.
Oven thermostats are not always accurate. Which? recommends checking with a stand-alone oven thermometer, because some ovens run noticeably hotter or cooler than the dial suggests. If cakes regularly brown too quickly or stay pale, adjust by 10°C and note what works.
What gas mark is used for common dishes?
- Gas mark ¼ to ½ (110–130°C): drying meringues and very slow cooking.
- Gas mark 1 to 2 (140–150°C): rich fruit cakes and long, gentle braises.
- Gas mark 3 to 4 (170–180°C): sponge cakes, biscuits and most everyday baking.
- Gas mark 5 to 6 (190–200°C): roasting meat and vegetables, pastry pies.
- Gas mark 7 to 9 (220–240°C): bread, scones, crisp roast potatoes and pizza.
These are typical ranges only; always follow the recipe and make sure meat and reheated food are cooked until steaming hot all the way through. For measuring ingredients accurately, our guide to how many ml are in a UK tablespoon covers spoon sizes, and the cooking converter handles weights and volumes.
Frequently asked questions
What is gas mark 4 in Celsius?
Gas mark 4 is 180°C in a conventional oven, 160°C in a fan oven and 350°F.
What is 200°C in gas mark?
200°C in a conventional oven is gas mark 6. In a fan oven, 200°C is equivalent to about gas mark 7.
What is gas mark 6 for a fan oven?
Gas mark 6 is about 180°C in a fan oven, which is 20°C below the 200°C conventional setting.
Is gas mark 3 160°C or 170°C?
Gas mark 3 is 325°F, which is 162.8°C. Many UK charts round it to 170°C, while others, including Which?, use 160°C; either is close enough for most recipes.
What is the highest gas mark?
Most UK gas cookers go up to gas mark 9, which is about 240°C or 475°F.
Sources
- Oven temperature conversion, Which? (gas mark, fan and Fahrenheit, and oven accuracy)
- Radiation Ltd, Grace’s Guide to British Industrial History (introduction of Regulo oven thermostats)
- National Physical Laboratory (UK temperature measurement standards)