Oven Temperature Converter
Convert oven temperature between Celsius, Fahrenheit, and Gas Mark. Includes fan/convection oven adjustment.
How to use this tool
- Enter temperature and from unit in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your fahrenheit and the full breakdown beneath it.
Formula
From Fahrenheit: °C = (°F − 32) × 5/9
From Celsius: °F = °C × 9/5 + 32
Gas Mark: Gas = (°F − 250) ÷ 25 (rounded to nearest 0.5)
Fan/Convection °C: Fan °C = °C − 20
How it works
The converter first normalises any input temperature to Celsius using the standard linear formula, then derives Fahrenheit, Gas Mark, and fan-oven temperature from that central value. Gas Mark is an approximation based on the traditional British scale where Mark 1 ≈ 275 °F and each mark increases by 25 °F. The fan adjustment subtracts 20 °C (approximately 35 °F) to account for the more efficient heat circulation in convection ovens.
A common mistake is using the conventional (non-fan) temperature setting on a fan-assisted oven without reducing it — this often causes over-browning or dry baked goods, since convection ovens cook roughly 20 °C hotter than their dial suggests relative to conventional recipes.
Worked example
Convert 350 °F to Celsius, Gas Mark, and fan temperature
- Start with 350 °F.
- Convert to Celsius: (350 − 32) × 5/9 = 318 × 5/9 ≈ 177 °C.
- Calculate Gas Mark: (350 − 250) ÷ 25 = 100 ÷ 25 = 4.
- Fan/convection temperature: 177 − 20 = 157 °C.
350 °F = 177 °C, Gas Mark 4, 157 °C fan/convection.
Common mistakes to avoid
- Forgetting to apply the fan/convection reduction -- recipes written for conventional ovens should be reduced by about 20 deg C (or 25 deg F) for a fan oven, and many bakers skip this, causing over-browning.
- Confusing UK Gas Mark with a temperature setting -- Gas Mark 6 is approximately 200 deg C / 400 deg F, not 6 deg C; treating the Gas Mark number as a temperature ruins the recipe.
- Using a Celsius value from a fan oven recipe in a conventional oven without adding the 20 deg C back -- the bake ends up under-done because the target was already reduced for a hotter fan environment.
Key terms
- Gas Mark
- A British oven temperature scale where Gas Mark 1 ≈ 275 °F (135 °C) and each full mark represents a 25 °F (14 °C) increment.
- Fan/Convection oven
- An oven with a fan that circulates hot air, cooking food more evenly and efficiently. Recipes for conventional ovens typically need a 20 °C (35 °F) reduction when using a fan oven.
- Fahrenheit (°F)
- The temperature scale used in the United States, where water freezes at 32 °F and boils at 212 °F at sea level.
- Celsius (°C)
- The metric temperature scale, used in most of the world and in professional cooking, where water freezes at 0 °C and boils at 100 °C at sea level.
Frequently asked questions
- What is Gas Mark 4 in Celsius?
- Gas Mark 4 is approximately 180°C (356°F) — a moderate oven temperature suitable for cakes and biscuits.
- What temperature is a moderate oven?
- A moderate oven is 160–180°C (325–350°F, Gas Mark 3–4).
- How much do I reduce for a fan oven?
- Fan (convection) ovens are typically 20°C (about 35°F) hotter than conventional ovens, so reduce the stated temperature by 20°C.