Gas mark

Formulae

In theory, the following formulae can be used to convert between gas mark values and Celsius.

For temperatures above 135 °C (gas mark 1), to convert gas mark to degrees Celsius (${\textstyle C}$), multiply the gas mark number (${\textstyle G}$) by 14, then add 121:

${\displaystyle \left(G\times 14\right)+121=C}$

For the reverse conversion:

${\displaystyle G={\frac {\left(C-121\right)}{14}}}$

These do not work for ${\textstyle G}$ less than 1, since the steps are given as halves (i.e., 1⁄2, 1⁄4). For temperatures below 135 °C (gas mark 1), to convert gas mark to degrees Celsius apply the following conversion:

${\displaystyle C={\frac {243-(25\times \log _{2}(G^{-1}))}{1.8}}}$

For the reverse:

${\displaystyle G=2^{(1.8C-243)/25}}$

Note that tables of temperature equivalents for kitchen use conventionally round Celsius values to the nearest 10 degrees, with steps of either 10 or 20 degrees between Gas Marks.^[4][5]

Conversion table

In practice, of course, a conversion table is used instead of the above formulae. The numbers in the conversion table below represent values that would actually be given in a recipe or set on a stove.^[5]

France: Thermostat

French ovens and recipes use a scale called the "Thermostat" (abbreviated "Th") that is based on the Celsius scale. Thermostat 1 equals 30 °C for conventional ovens, increasing by 30 °C for each whole number along the scale.^[6]

Germany: Stufe

In Germany, "Stufe" (the German word for "step") is used for gas cooking temperatures. Gas ovens are commonly marked in steps from 1 to 8, corresponding to:

Other ovens may be marked on a scale of 1–7, where Stufe 1⁄2 is about 125 °C in a conventional oven, Stufe 1 is about 150 °C, increasing by 25 °C for each subsequent step, up to Stufe 7 at 300 °C.^[7]