Oven Temperature Conversion Calculator

Oven Temperature Conversion Calculator

This free oven temperature converter instantly translates between Celsius (°C), fan oven Celsius, Fahrenheit (°F) and Gas Mark — the four settings you'll find on British and Commonwealth recipes and ovens. Enter any one value and it returns the equivalent in all four, plus whether that's a slow, moderate or hot oven. It's built for UK home cooks juggling old recipe books that quote Gas Mark, American recipes in Fahrenheit, and a modern fan-assisted oven that runs hotter than a conventional one.

Most charts online are static images you have to squint at. This is a proper bidirectional calculator: convert from Gas Mark, Celsius, fan Celsius or Fahrenheit, in either direction, with the standard UK rule that a fan oven runs about 20°C lower than a conventional oven at the same browning result. Whether you're following Mary Berry, an old Be-Ro book, or a US baking blog, you'll get the right dial setting for your oven.

How the oven temperature conversion works

The calculator uses two simple, exact relationships plus the standard UK Gas Mark chart:

• Celsius ↔ Fahrenheit: the exact formula °F = (°C × 9 ÷ 5) + 32, and °C = (°F − 32) × 5 ÷ 9.
• Conventional ↔ Fan: a fan (convection) oven is set roughly 20°C lower than a conventional oven to achieve the same cooking result, because the moving air heats food more efficiently.
• Gas Mark: uses the canonical UK chart (Gas Mark 4 = 180°C = 350°F = "moderate"), with each step changing by roughly 25°F / 14°C above Gas Mark 1.

Here is the full reference chart the calculator is built on:

Note: fan oven figures are the conventional value minus 20°C, rounded to the nearest practical dial setting. Always check your oven's handbook and use an oven thermometer for precision baking.

Worked example

Say a vintage UK recipe tells you to bake a Victoria sponge at Gas Mark 4, but you have a modern fan oven and a recipe app that wants Fahrenheit. Select "Gas Mark" and choose 4. The calculator returns:

• Conventional oven: 180°C
• Fan oven: 160°C (180 − 20)
• Fahrenheit: 356°F (180 × 9 ÷ 5 + 32 = 356; recipe books usually round this to the 350°F dial mark)
• Oven heat: Moderate

So you'd set a fan oven to 160°C. If instead you typed 180 with "Celsius" selected, you'd get the same row back: 180°C conventional, 160°C fan, 356°F, Gas Mark 4.

Frequently asked questions

What temperature is Gas Mark 4?

Gas Mark 4 is 180°C in a conventional oven, 160°C in a fan oven, and 350°F. It is described as a "moderate" oven and is the most common roasting and baking temperature in UK recipes.

How much lower should I set a fan oven?

The standard UK rule is to set a fan (convection) oven about 20°C lower than a conventional oven for the same result. So a recipe stating 200°C conventional becomes 180°C fan. Some manufacturers suggest 15–25°C, so check your oven handbook.

How do I convert Celsius to Fahrenheit for an oven?

Multiply the Celsius figure by 9, divide by 5, then add 32. For example 180°C × 9 ÷ 5 = 324, plus 32 = 356°F (rounded to 350°F on most ovens, which is Gas Mark 4).

What is a "hot" oven in Gas Mark terms?

A hot oven is Gas Mark 7–8, which is 220–230°C conventional (200–210°C fan) or 425–450°F — used for crisp roast potatoes, bread and pastry. A "very hot" oven is Gas Mark 9 (240°C / 475°F).

Source

Conversion figures follow the canonical UK oven chart published by reference cookery sources, cross-checked against the standard Gas Mark table. See the Delia Online conversion tables and the Gas mark reference (Wikipedia) for the underlying Celsius, Fahrenheit and Gas Mark equivalents.

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