What is gas mark?
A gas mark is a numbered oven setting used on many UK gas ovens. It is a practical way to describe oven heat, alongside Celsius, Fahrenheit and fan oven temperatures.
A gas mark is a numbered oven setting used to control the heat of a gas oven. In UK recipes, gas marks are often shown alongside Celsius and sometimes Fahrenheit.
For example, gas mark 4 is commonly treated as about 180°C in a conventional oven, or about 160°C fan.
Why gas marks matter
Many UK recipes still use gas marks, especially older cookbooks, baking guides and printed recipe cards. If your oven uses Celsius or fan settings instead, you need an approximate conversion before cooking.
Gas marks are useful for quick instructions, but oven temperatures are not perfectly exact. Ovens vary, fan ovens cook differently, and some foods need judgement based on browning, texture and timing.
Common gas mark conversions
Use this table as a practical guide. Exact results vary by oven, so treat these as common kitchen equivalents rather than laboratory-precise values.
| Gas mark | Conventional oven | Fan oven estimate | Fahrenheit estimate |
|---|---|---|---|
| Gas mark 1 | 140°C | 120°C fan | 275°F |
| Gas mark 2 | 150°C | 130°C fan | 300°F |
| Gas mark 3 | 170°C | 150°C fan | 325°F |
| Gas mark 4 | 180°C | 160°C fan | 350°F |
| Gas mark 5 | 190°C | 170°C fan | 375°F |
| Gas mark 6 | 200°C | 180°C fan | 400°F |
| Gas mark 7 | 220°C | 200°C fan | 425°F |
| Gas mark 8 | 230°C | 210°C fan | 450°F |
| Gas mark 9 | 240°C | 220°C fan | 475°F |
Gas mark vs Celsius
Celsius gives a temperature number. Gas mark gives a numbered oven setting. A recipe might say 180°C or gas mark 4; in everyday UK cooking, those are usually treated as equivalent for a conventional oven.
180°C conventional oven ≈ gas mark 4
200°C conventional oven ≈ gas mark 6
Gas mark vs fan oven
Fan ovens move hot air around the oven, so many recipes use a lower fan temperature than the conventional oven temperature. A common practical rule is to reduce the conventional Celsius temperature by around 20°C.
fan temperature ≈ conventional Celsius temperature − 20°C
So a recipe written as gas mark 4 / 180°C is often cooked at about 160°C fan.
How to convert gas mark
The easiest method is to use a lookup table or the Oven Temperature Converter. Gas marks do not increase in a perfectly neat formula for everyday cooking, so a table is usually more useful than mental maths.
- Find the gas mark in the recipe.
- Convert it to conventional Celsius.
- Reduce by around 20°C if using a fan oven.
- Check the food near the end of cooking time, especially for baking.
Quick answers
| Question | Practical answer |
|---|---|
| What gas mark is 180°C? | Gas mark 4 |
| What gas mark is 200°C? | Gas mark 6 |
| What is gas mark 5? | About 190°C, or about 170°C fan |
| Is gas mark exact? | No. It is a practical oven setting and varies by oven. |
FAQs
What gas mark is 180°C?
180°C in a conventional oven is commonly treated as gas mark 4. For a fan oven, the equivalent is often around 160°C fan.
What gas mark is 200°C?
200°C in a conventional oven is commonly treated as gas mark 6. For a fan oven, the equivalent is often around 180°C fan.
Is a gas mark the same as a temperature?
A gas mark is an oven setting rather than a direct temperature reading. It is usually converted to Celsius or Fahrenheit using a common oven conversion table.
Do fan ovens use gas marks?
Fan ovens normally use Celsius settings rather than gas marks. If a recipe gives a gas mark, convert it to conventional Celsius first, then reduce by around 20°C for a fan oven as a practical estimate.