Oven Temperature Converter

Multiply the Celsius figure by 9, divide by 5 and add 32: 180 °C is exactly 356 °F, and that is gas mark 4. The conversion has no rounding in it; the gas mark does, because it is a stepped dial with nine positions rather than a continuous scale.

Two temperature scales can disagree about two separate things: where zero sits, and how large a single degree is. Celsius puts the freezing point of water at 0 and its boiling point at 100; on the Fahrenheit scale those same two points are 32 and 212. A hundred Celsius degrees therefore span a hundred and eighty Fahrenheit degrees, which is the 9/5 in the formula, and the 32 closes the gap between the zeros. Both corrections are needed, in that order: the default setting of 180 °C gives 180 × 9/5 = 324, and adding 32 makes exactly 356 °F. Nothing is rounded away, because the relation is a definition rather than a measurement. The gas mark alongside is a different kind of number altogether — a numbered dial position tied to a Celsius value by convention, and 180 °C is mark 4. What all of this converts is a setting, not the heat inside your oven. A domestic oven drifts by more than the six degrees separating 350 °F from 356 °F.