Oven Temperature Calculator
Convert oven temperatures between Celsius, Fahrenheit, gas mark and fan.
Please note: Cooking guides only. Times and temperatures vary with oven calibration, altitude, starting temperature and cut. For anything where safety matters — poultry, pork, sous vide, preserving — use a probe thermometer and follow your national food safety guidance rather than a calculated time.
What the Oven Temperature Calculator does
Recipes quote oven temperatures in three incompatible systems, and fan ovens add a fourth complication by running effectively hotter than the dial. Converting means picking a reference — the conventional Celsius setting — and expressing everything else relative to it.
Formula
°F = °C × 9 ÷ 5 + 32°C = (°F − 32) × 5 ÷ 9Fan setting = Conventional − 20 °CGas mark 4 = 180 °C = 356 °F
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Temperature | number | Yes | — |
| Scale | one of 3 options | Yes | — |
| Your oven is | one of 2 options | Yes | — |
| Fan reduction | °C | Optional | Most fan ovens run 20 °C hotter than the dial suggests. Accepts 0 or more. |
How to use it
- Choose Scale and Your oven is.
- Enter Temperature.
- Optionally add Fan reduction.
- Select Calculate.
Worked example
A recipe calling for 180 °C in a conventional oven.
- Temperature
- 180
- Scale
- Celsius
- Oven
- Conventional
180 °C is 356 °F and gas mark 4. In a fan oven, set it to 160 °C instead.
Reading the result
- A fan (convection) oven cooks faster at a given dial temperature than a conventional one because moving air transfers heat more efficiently — the conversion lowers the equivalent conventional temperature by roughly 20°C/25°F to compensate, not because the fan oven runs genuinely cooler.
Common mistakes
- Converting the temperature between scales but leaving the original recipe's cooking time unchanged when also switching between fan and conventional mode. The temperature conversion and the timing adjustment are two separate corrections.
Frequently asked questions
Why do fan ovens need a lower setting?
Moving air transfers heat far more efficiently than still air, so food at the same dial temperature cooks faster and browns harder. Dropping 20 °C compensates.
How accurate are gas marks?
Approximate. The steps are roughly 14 °C apart at the top of the range and 10 °C at the bottom, and individual ovens vary by more than that anyway.
Method and sources
Method. Exact conversion between Celsius, Fahrenheit and gas mark, with fan and conventional oven equivalents.
Assumptions
- The fan adjustment follows the common convention of roughly 20 °C lower than a conventional setting.
Limitations
- Celsius and Fahrenheit convert exactly; gas marks and fan equivalents are conventions and ovens vary around them.
- Domestic ovens commonly run 10–20 °C away from their dial, and the difference is not constant across the range — an oven thermometer settles it where the setting matters.
Sources
- None for the temperature conversion, which is exact arithmetic — Not applicable. The Celsius-Fahrenheit relationship. The fan and gas-mark equivalents are conventions, and are described as such rather than cited.