Oven Temperature Converter
Convert oven temperatures between Fahrenheit, Celsius and gas marks, then adjust for a fan (convection) oven or an air fryer — with the dial setting to use, the cooking-time change and a full oven chart.
How it works
°C = (°F − 32) × 5⁄9 · °F = °C × 9⁄5 + 32 · gas mark n (1–10) = 250 + 25n °F; mark ½ = 250 °F, ¼ = 225 °F · fan or air fryer ≈ conventional − 25 °F (or − 20 °C) · air-fryer time ≈ oven time × 0.8
The scale conversion is the standard Fahrenheit–Celsius formula. Recipes round the result to the steps ovens and cookbooks use: 25 °F in American recipes and 10 °C in metric ones. 350 °F becomes 180 °C, not 176.7. Gas marks are the British gas-cooker scale: mark 1 is 275 °F and each mark adds 25 °F, with ¼ and ½ below it. A fan (convection) oven moves hot air over the food, so it cooks faster than a conventional oven at the same setting. The usual correction is 25 °F lower in the US, or 20 °C lower on UK and European charts. An air fryer is a small, strong convection oven: take about the same amount off the temperature and expect the food to be done in roughly 20% less time. Pick the oven the recipe was written for and the one you are cooking in, and the calculator applies the change, rounds it to a dial setting and finds the place in the full chart.
Worked example
A US recipe says 350 °F. 350 − 32 = 318, and 318 × 5 ⁄ 9 = 176.7 °C, which you would set as 180 °C (gas mark 4, "moderate"). Baking in a fan oven with the 25 °F rule: 350 − 25 = 325 °F, about 160 °C. In an air fryer, a 25-minute oven time becomes about 25 × 0.8 = 20 minutes, so start checking then. Going the other way, a UK recipe for 200 °C fan is 220 °C (425 °F) in a conventional oven on the 20 °C rule.
Frequently asked questions
Why do recipes round the converted number?
A home oven swings about ±25 °F around its set point while it cycles, so the gap between 177 and 180 °C makes no difference. Recipes use round steps (25 °F, or 10 °C) and so does this calculator’s dial setting. Choose “nearest degree” under More options if you want the exact figure.
How much lower should a fan or convection oven be?
About 25 °F lower in American practice, or 20 °C lower on most UK and European charts. 180 °C conventional is 160 °C fan. Some cooks take only 15 °C off for delicate cakes. If a recipe already gives a fan temperature, use it as it is: lowering it again is a common mistake.
How do I convert an oven recipe for an air fryer?
Lower the temperature by about 25 °F (15–20 °C) and start checking about 20% sooner. A 400 °F, 20-minute oven recipe becomes roughly 375 °F for 16 minutes. Air fryers usually max out near 400 °F, and they suit roasting and crisping better than cakes or large roasts.
What temperature is gas mark 4, 6 or 7?
Gas mark 4 is 350 °F (180 °C), mark 6 is 400 °F (200 °C) and mark 7 is 425 °F (220 °C). Mark 1 is 275 °F and each mark adds 25 °F. The full chart under the results lists every mark with its fan equivalent.
What if my oven runs hot or cold?
Thermostats drift, and being 15–25 °F out is common. A standalone oven thermometer, left in for 20 minutes after preheating, shows the true offset. Then correct every recipe by the same amount.
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This calculator is for educational purposes. Double-check important results before acting on them.