gas mark

Definition

Food

  • A scale of temperature, written as GM, peculiar to gas ovens and based on an arbitrary scaling of the first oven thermostat when °F were in use. The relationship to temperature is as follows:- GM1/4 110°C, 225°F; GM1/2 130°C, 250°F; GM1 140°C, 275°F; and thereafter 25°F per unit until GM9 240°C, 475°F.
http://www.dictionarycentral.com/definition/gas-mark.html