A 350 °F oven is 176.7 °C, which European recipes write as 180 °C — and a fan oven wants about 20 °C less again, so 160 °C fan. The conversion itself is subtract 32 and divide by 1.8; everything awkward about baking across the two systems comes after that, from rounding to a dial that only has certain numbers on it.
US baking temperatures step in 25 °F increments, which is 13.9 °C. European ovens step in 10 °C. The two ladders do not have rungs in the same places, which is why converted recipes always need a decision rather than a number.
What does each American temperature become?
The exact conversion, the number a European recipe would print, and the fan equivalent.
| Fahrenheit | Exact Celsius | Conventional | Fan | Gas mark |
|---|---|---|---|---|
| 275 °F | 135.0 °C | 140 °C | 120 °C | 1 |
| 300 °F | 148.9 °C | 150 °C | 130 °C | 2 |
| 325 °F | 162.8 °C | 160 °C | 140 °C | 3 |
| 350 °F | 176.7 °C | 180 °C | 160 °C | 4 |
| 375 °F | 190.6 °C | 190 °C | 170 °C | 5 |
| 400 °F | 204.4 °C | 200 °C | 180 °C | 6 |
| 425 °F | 218.3 °C | 220 °C | 200 °C | 7 |
| 450 °F | 232.2 °C | 230 °C | 210 °C | 8 |
Notice that the rounding is not consistent. At 325 °F the printed European figure rounds down by 2.8 °C; at 350 °F it rounds up by 3.3 °C. Recipe conventions were set independently in each system and then matched approximately, so the mapping is a lookup rather than a formula.
Why does a fan oven need twenty degrees less?
Because moving air transfers heat faster than still air, so food at the same dial temperature cooks harder in a fan oven. The usual adjustment is 20 °C, or about 25 °F, and the effect is on cooking rate rather than on the temperature the food eventually reaches.
Timing shifts too. A fan oven at the reduced temperature typically finishes a few minutes earlier than a conventional one, and it browns more evenly because there is no hot spot at the back. For anything that rises — soufflés, choux, a delicate sponge — the even heat helps and the moving air can dry the surface, so covering for the first part of the bake is a common fix.
Does the dial tell the truth?
Rarely, and this matters more than the conversion. Domestic ovens routinely run 10 to 20 °C away from their setting, and they cycle around it rather than holding it, so the temperature at any given minute may be well off the average.
An oven thermometer costs little and settles the question permanently. If yours runs 15 °C hot, a converted recipe calling for 180 °C wants a dial setting of 165, and no amount of careful conversion will find that out for you.
Position matters as much as the number. The top of a conventional oven is hotter than the bottom, sometimes by more than the whole fan adjustment, which is why recipes specify a shelf.
What about the other measurements in the recipe?
Volume is the bigger problem. American recipes measure flour and sugar by cup, and a cup of flour varies by a third depending on whether it was scooped or spooned. Where a converted recipe fails, the temperature is usually innocent and the cup is usually guilty.
A US cup is 236.6 ml, a stick of butter is 113 g, and an American pint is 473 ml against an imperial 568 ml. Weighing the dry ingredients removes almost all of the variance a converted recipe suffers from.
What about internal meat temperatures?
These convert as ordinary temperatures, and the round numbers are again on the Fahrenheit side. The US Department of Agriculture safe minimum internal temperatures are 165 °F for poultry, 160 °F for ground meat, and 145 °F for whole cuts of beef, pork, veal and lamb with a three-minute rest.
In Celsius those are 73.9, 71.1 and 62.8 °C. European guidance tends to be written around 75 °C, which is 167 °F — a slightly higher figure reflecting a different round number rather than a different piece of food science.
A probe thermometer is the only way to use any of these. Oven temperature and internal temperature are separate measurements, and it is entirely normal for a joint to sit at 62.8 °C in the middle of a 220 °C oven for an hour.
Questions people ask
Is 350 °F exactly 180 °C? No, it is 176.7 °C. The 180 is the nearest rung on the European ladder, and the 3.3 °C difference is smaller than the error in most domestic ovens.
Should I use the exact figure if my oven allows it? You can, and it will make no observable difference. Setting 177 rather than 180 is precision the appliance cannot deliver.
Where do gas marks come from? A separate British scale that predates numbered dials. Gas mark 4 is 180 °C, and each mark is 25 °F, which is why the gas ladder lines up with the Fahrenheit one and not the Celsius one.
What about air fryers? They are small fan ovens, so the fan adjustment applies and then some — most recipes want another 10 °C off and a shorter time, because the chamber is small and the airflow is fierce.
Convert, round to the rung your dial has, then subtract 20 for a fan. Fahrenheit to Celsius does the first step, Celsius to Fahrenheit goes the other way for a European recipe in an American kitchen, and litres to gallons covers the volumes that cause the rest of the trouble.