What a gas mark is
British gas ovens are numbered 1/4 to 9 rather than marked in degrees. The scale is roughly linear in Fahrenheit: gas mark = (°F − 250) ÷ 25. Gas 4, the most common setting, is 350 °F or 180 °C.
The full table
- Gas 1 = 275 °F / 140 °C · Gas 2 = 300 °F / 150 °C
- Gas 3 = 325 °F / 170 °C · Gas 4 = 350 °F / 180 °C
- Gas 5 = 375 °F / 190 °C · Gas 6 = 400 °F / 200 °C
- Gas 7 = 425 °F / 220 °C · Gas 8 = 450 °F / 230 °C · Gas 9 = 475 °F / 240 °C
Fan ovens and gas
Fan-assisted ovens are usually electric, so a gas-mark recipe needs converting twice: gas → conventional °C, then minus 20 °C for the fan. Gas 4 (180 °C) becomes 160 °C fan.
Why the marks persist
They are printed on the dial of millions of UK ovens and appear in every British cookbook. Even metric recipes often give a gas mark as a backup — which makes this conversion one of the most-searched in British kitchens.
Frequently Asked Questions
What is gas mark 4 in Celsius?
180 °C (350 °F) — the standard baking setting.
What is gas mark 6?
200 °C / 400 °F, used for roasting and fast bakes.
Is gas mark 9 the maximum?
Yes on domestic ovens; commercial ranges can go higher.
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