Oven Temperature Converter
Recipes arrive in mixed units — a British bake in gas mark, an American one in Fahrenheit, a European one in Celsius, and many modern ovens in fan-assisted Celsius. Reading the wrong one means a burnt top or a raw middle. This converter takes any one of those and returns all the others, including the fan setting that most convection ovens expect.
Enter the temperature you know and pick its scale. The calculator returns the equivalent in °C, °F, gas mark and fan °C (conventional minus roughly 20°C). Gas marks outside the standard 1–9 range are shown as the nearest mark with a note, since ovens do not step beyond them.
It is the small conversion that saves a borrowed recipe — the difference between a British bake written in gas mark and the fan oven you actually own, resolved in one glance instead of a frantic mid-prep search.
Enter your values to see the result.
How this is calculated
Every input is first reduced to a conventional Celsius value. A Fahrenheit input is converted with °C = (°F − 32) × 5/9. A fan input is treated as conventional minus 20°C, so conventional = fan + 20. A gas mark input is mapped through the standard British table: Mark 1 = 140°C, 2 = 150, 3 = 165, 4 = 180, 5 = 190, 6 = 200, 7 = 220, 8 = 230, 9 = 240. From that single Celsius value, all other scales are derived.
Fahrenheit is derived as °F = °C × 9/5 + 32. The fan setting is conventional Celsius minus 20, reflecting that a convection oven circulates hot air and cooks at a lower set temperature for the same result. The gas mark output is the nearest standard mark to the Celsius value, since gas ovens step in fixed increments and cannot be set between marks.
The 20°C fan adjustment is the widely used convention, not a physical constant — some ovens need 25°C less, some only 15°C. The gas mark table is the standard British mapping; some sources quote slightly different values for individual marks. Oven thermostats are also imprecise and many ovens run 10–25°C off their setting, so treat the output as a reliable starting point and verify with an oven thermometer for critical baking.
Worked example
A US recipe calls for 350°F. You have a fan oven in Celsius.
- 1Convert to conventional Celsius: (350 − 32) × 5/9 = 176.7 ≈ 177°C.
- 2Fan setting = 177 − 20 = 157 ≈ 160°C fan.
- 3Nearest gas mark to 177°C is Mark 4 (180°C).
- 4So 350°F ≈ 180°C conventional ≈ 160°C fan ≈ Gas Mark 4.
Frequently asked questions
- What is a fan oven temperature?
- A fan-assisted (convection) oven circulates hot air and cooks more evenly, so recipes typically call for a setting about 20°C lower than a conventional oven. The converter shows fan °C as the conventional Celsius value minus 20.
- How is gas mark converted?
- Gas mark is a British scale from ¼ to 9 mapped to specific Celsius values. The converter uses the standard table: Gas 1 = 140°C, 2 = 150, 3 = 165, 4 = 180, 5 = 190, 6 = 200, 7 = 220, 8 = 230, 9 = 240. Values between marks are rounded to the nearest mark.
- Why does my oven run hot or cold?
- Oven thermostats are imprecise and many ovens run 10–25°C off their setting. Use an oven thermometer to calibrate, and treat these conversions as a starting point rather than an exact guarantee.
- Why is the fan setting lower than conventional?
- A fan-assisted oven blows hot air across the food, transferring heat more efficiently than the still air in a conventional oven. To get the same cooking result, recipes set a fan oven roughly 20°C lower than a conventional one. Some ovens need a slightly larger or smaller drop, so adjust to your own oven.
- What about gas mark ¼ and ½?
- They exist for very low temperatures (Mark ¼ ≈ 110°C, ½ ≈ 120°C, 1 = 140°C). This converter focuses on the common Mark 1–9 range; for very slow ovens below 135°C, use the Celsius value directly rather than the gas mark output.
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Method: standard temperature conversions plus the British gas mark table (Mark 1–9) and a 20°C fan-oven adjustment. No external data source. Last updated: September 2026.
These results are general estimates from established formulas and conversion factors. Paint coverage, tile yields, concrete volumes, fuel economy, oven behaviour and clothing and shoe sizes vary by product, surface, vehicle, oven and brand. Always confirm with your supplier, the product label or the brand’s own size chart before buying or acting on a calculation.