Gas Mark to Fahrenheit Converter

A gas mark is the temperature scale on UK and Irish gas ovens. The dial runs from gas mark 1/4 (the coolest setting) up to gas mark 9, with each whole step about 25°F apart. Older British and Irish recipes list oven temperatures as gas marks instead of degrees, so you need a quick conversion to use them.

For gas mark 1 and above, multiply the gas mark by 25 and add 250 to get degrees Fahrenheit. So gas mark 4 is 25 times 4 plus 250, which is 350°F, and gas mark 6 is 400°F. The two settings below 1 do not follow this formula: gas mark 1/4 is 225°F and gas mark 1/2 is 250°F by convention.

Gas mark 4 is 350°F. The exact Celsius conversion is 176.7°C, but cookery charts and oven dials round this to a tidy 180°C. Gas mark 4 is a moderate oven, the most common setting for cakes, roasts, and everyday baking.

Subtract 250 from the Fahrenheit value, then divide by 25. For example, 375°F gives 375 minus 250 divided by 25, which is gas mark 5. Switch this tool to temperature to gas mark mode and it snaps any recipe temperature to the nearest standard mark so you know where to set the dial.

The low settings are fixed points on the standard cookery chart rather than formula outputs. Gas mark 1/4 is 225°F (about 110°C) and gas mark 1/2 is 250°F (about 130°C). Counted as named steps, 1/4, 1/2, 1, 2 and upward each sit 25°F apart, starting from 225°F.

The Fahrenheit values are exact, and the exact Celsius comes from the Fahrenheit reading minus 32, times 5, divided by 9. Published oven charts round Celsius to convenient dial numbers, so gas mark 4 shows as 180°C even though the precise figure is 176.7°C. This converter shows both the rounded dial value and the exact figure.