Oven Temperature Converter

How to use the oven temperature converter

1. Fill in the fields — they start with a worked example.
2. Read the answer, and the arithmetic shown beneath it.
3. Copy the results, or adjust the inputs to compare scenarios.

About this tool

Three systems describe the same oven. British recipes give a gas mark, most of Europe gives Celsius, American recipes give Fahrenheit, and a fan oven needs a different number again from any of them. A recipe that crosses one of those borders is the usual reason a cake burns.

The fan adjustment is the one that catches people. A fan circulates hot air, so heat reaches the food faster and the same dial setting cooks harder. The convention is to set a fan oven about twenty degrees Celsius lower than a conventional recipe states, which is why 180°C conventional becomes 160°C fan. Manufacturers vary, and some ovens make the adjustment internally, so the oven's own manual beats any general rule.

Gas marks are not a linear scale and cannot be calculated — they are a lookup table, spaced roughly ten to twenty degrees apart with fractional marks at the bottom for slow cooking. So the mark shown here is the closest one rather than an exact equivalent, and the difference in degrees is shown with it.

Oven thermostats are also less accurate than their dials imply, commonly out by ten or fifteen degrees and rarely even front to back. For anything sensitive, an oven thermometer tells you more than any conversion can.

Common uses

• Cooking an American recipe in a Celsius oven.
• Converting a gas mark in an older cookbook to a modern dial.
• Adjusting a conventional oven temperature for a fan oven.

Frequently asked questions

What is 180°C in Fahrenheit?

356°F, which recipes round to 350°F. In a fan oven use about 160°C, and on gas it is mark 4.

How much lower should a fan oven be set?

About twenty degrees Celsius below a conventional recipe, because circulating air transfers heat faster. Some ovens apply the reduction themselves, so check the manual.

Can gas marks be calculated from Celsius?

Not with a formula — the scale is not linear. It is a lookup table, so the nearest mark is the best available answer and the gap in degrees is worth knowing.