Convert oven temperatures between Celsius, Fahrenheit and British gas marks, with fan-oven adjustment and the Brazilian recipe names.
The Celsius-to-Fahrenheit conversion is a formula — multiply by nine fifths and add thirty-two — and it gives an exact answer every time. Gas marks are not a formula: they are a numbered scale that the British gas industry put on cooker knobs in the 1940s, each click roughly 14 °C apart. The Fahrenheit values printed next to each gas mark in the Which? table are not conversions of the Celsius values: the British table rounds both to convenient numbers independently, so gas mark 4 is published as 180 °C and 350 °F even though 180 °C is really 356 °F. This page shows you both the published British table and the Celsius-Fahrenheit arithmetic, and names the gap when the two disagree. The table runs from ¼ to 10, covering roughly 110 °C to 260 °C — enough for everything from meringues to pizza.
Fan ovens — called convection, turbo or air-fry in Brazil — circulate hot air with a rear fan, which transfers heat to the food surface faster and cooks more evenly than a conventional oven that relies on radiation from a static element. The practical consequence is that a recipe written for a conventional oven needs the temperature lowered, usually by about 20 °C or one gas mark, when cooked in a fan oven. That rule of thumb comes from oven manufacturers, not from food science, and some recipes also ask you to shorten the baking time instead of lowering the temperature. The page works out the adjustment for you, and says that it is a rule of thumb rather than a conversion. Brazilian recipes rarely distinguish between the two, and almost never mention whether the fan should be on, which is one reason the same cake recipe comes out differently in two kitchens even when both set the dial to the same number.
What Brazilian recipes call "forno médio" or "forno alto" is the loosest convention of all: there is no technical standard behind those words, no published definition from any Brazilian standards body, and the ranges genuinely vary from cookbook to cookbook. One puts "forno médio" at 160 °C, another at 180 °C, and neither is wrong because neither is a standard. The page maps the temperature you typed to the names in common use and says upfront that they are custom, not a norm. One thing that matters more than any of these conversions is the thermostat itself: home oven thermostats are commonly off by 10 to 25 °C in either direction, and the temperature is not uniform inside the cavity — top, bottom and back can differ by more than the margin between "medium" and "hot". An oven thermometer costs a few reais and changes cooking outcomes more than getting the conversion right to the last degree. Everything runs in your browser: the temperature you type stays on your device.
°F = °C × 9/5 + 32. Gas marks are a discrete scale, not a formula: mark 1 = 140 °C / 275 °F, each step ≈ 14 °C. Fan-oven rule of thumb: subtract about 20 °C from the conventional temperature.
The British table publishes it as 180 °C and 350 °F. Those two are not exact conversions of each other — 350 °F is 176.7 °C. The table rounds both to round numbers independently, so this page shows you the published values and the arithmetic side by side.
Usually yes: about 20 °C less, or one gas mark down. A fan circulates hot air and cooks faster, so the same dial setting is effectively hotter. Some recipes adjust the time instead — check the recipe first, and use the page's fan adjustment if it does not say.
It depends on who wrote the recipe. Most Brazilian sources put "forno médio" somewhere between 160 °C and 200 °C, but the ranges are not standardised and different cookbooks draw the lines in different places. Treat it as a hint, and prefer a recipe that gives you a number.
Because home oven thermostats are commonly off by 10-25 °C, and the temperature is not uniform inside — top, bottom and back can differ. An oven thermometer is the cheapest fix in the kitchen.
No. The conversion is arithmetic and the gas mark table is embedded in the page. No data is sent anywhere.
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