Understanding Oven Temperatures
If you've ever opened a recipe book and seen "180°C" when your oven only shows gas marks, or tried to follow an American recipe with "350°F" on a UK fan oven, you know how confusing oven temperatures can get. There are four common ways to measure oven heat in the kitchen — and they all describe the same thing differently.
What is gas mark?
Gas mark is a temperature scale used on gas cookers, almost exclusively in the UK and Ireland. Each gas mark corresponds to a specific temperature, going from gas mark ¼ (very cool, around 110°C) up to gas mark 9 (very hot, around 240°C). The system was designed by the British gas industry in the 1940s and stuck around because British recipe books continued to use it long after electric ovens with degree displays became common.
Fan oven vs conventional oven
A fan oven (also called a convection oven) circulates hot air using a built-in fan, which cooks food faster and more evenly than a conventional oven at the same temperature. As a rule of thumb, you should reduce the temperature by 20°C when using a fan oven compared to a conventional one. So a recipe that says "180°C" actually means "160°C in a fan oven."
Celsius vs Fahrenheit
Celsius is used in the UK, Europe and most of the world. Fahrenheit is used almost exclusively in the United States. The conversion formula is: °F = (°C × 9/5) + 32. So 180°C = 356°F, though most American recipes round this to 350°F for convenience.
Frequently Asked Questions
What is 180 in gas mark?
180°C is gas mark 4 in a conventional oven. This is described as "moderate" heat — perfect for most baking, including cakes, biscuits and casseroles. In a fan oven, you'd use 160°C. In Fahrenheit, that's 350°F.
What is 180 degrees Celsius in gas mark?
180 degrees Celsius equals gas mark 4. The full conversion: 180°C = gas mark 4 = 350°F = 160°C fan. It's the most commonly used baking temperature in British recipes.
What is 200 degrees in gas mark?
200°C is gas mark 6 in a conventional oven, or 180°C in a fan oven. This is "hot" oven heat — used for roasting vegetables, baking bread, and finishing roast potatoes for crispness. In Fahrenheit it's 400°F.
What is gas mark 6 in degrees?
Gas mark 6 equals 200°C in a conventional oven, 180°C in a fan oven, or 400°F. It's classified as "hot" and is one of the most commonly used temperatures in British cooking — ideal for roasting, baking bread and reheating meals.
What is gas mark 4 in degrees?
Gas mark 4 equals 180°C in a conventional oven, 160°C in a fan oven, or 350°F. It's described as "moderate" heat and is the standard temperature for most baking — cakes, cookies, casseroles and many traditional bakes.
What is 350°F in gas mark?
350°F is gas mark 4 (180°C in a conventional oven, 160°C in a fan oven). This is the most common temperature in American baking recipes, used for cookies, brownies, cakes and many casseroles.
How do I convert a recipe for a fan oven?
Reduce the temperature by 20°C when using a fan oven compared to a conventional oven. So a recipe calling for 180°C becomes 160°C in a fan oven. You can also reduce cooking time by about 10-15% because fan ovens cook faster and more evenly. Always check your food a few minutes earlier than the recipe suggests when using a fan oven.
Why do British recipes use gas mark?
Gas marks are a legacy of when most British homes had gas cookers without temperature dials. The system was simpler than calibrating a precise temperature — you just turned the knob to a number from 1 to 9. Even though most modern ovens display degrees in Celsius, traditional British recipe books and home cooks still use gas marks out of habit.
Is 180°C the same as 180°F?
No — they're very different. 180°C is 356°F (very hot, suitable for baking). 180°F is only 82°C (warm, not even hot enough to cook food). Always check whether a recipe is in Celsius or Fahrenheit before using your oven.