Oven Temperature Guide: Gas Mark, Celsius, and Fahrenheit
By Marcus Thompson · Published
Open a recipe from a different country and the oven temperature instruction might say “180°C,” “350°F,” or “gas mark 4” — three completely different-looking numbers that, in this case, all mean roughly the same oven setting. If you’ve ever guessed at the conversion and ended up with an undercooked or burnt dish, this guide is for the next time it happens.
The three systems at a glance
- Celsius (°C) is used throughout Europe, Australia, and most of the world for oven dials and recipes.
- Fahrenheit (°F) is standard in the United States.
- Gas mark is a numbered scale (typically 1 through 9) used on older and some current UK gas ovens, where each step corresponds to roughly a 25°F (about 14°C) increase.
Full conversion table
| Gas Mark | Celsius | Fahrenheit | Description |
|---|---|---|---|
| ¼ | 110°C | 225°F | Very low / warming |
| ½ | 120°C | 250°F | Very low |
| 1 | 140°C | 275°F | Low |
| 2 | 150°C | 300°F | Low |
| 3 | 160°C | 325°F | Moderately low |
| 4 | 180°C | 350°F | Moderate |
| 5 | 190°C | 375°F | Moderately hot |
| 6 | 200°C | 400°F | Hot |
| 7 | 220°C | 425°F | Hot |
| 8 | 230°C | 450°F | Very hot |
| 9 | 240°C | 475°F | Very hot |
These figures are the standard rounded equivalents used by UK cookbooks and oven manufacturers — they’re rounded to the nearest 10°C / 25°F for practical dial settings, not exact mathematical conversions.
The exact formula vs. the rounded table
The exact Celsius-to-Fahrenheit formula is °F = (°C × 9/5) + 32. Applied precisely, 180°C converts to exactly 356°F — but the table above lists 350°F for gas mark 4. This isn’t an error; oven dials and recipe instructions are written in round numbers because home ovens don’t hold temperature precisely enough for a 6°F difference to matter. When converting a recipe, use the table’s rounded values, not the mathematically exact ones — 350°F and 180°C are treated as equivalent in practice, and that’s what recipe writers mean when they list both.
For situations where you do need the exact conversion — for instance, converting a specific temperature reading from a thermometer or a scientific process — use the Celsius to Fahrenheit converter, which applies the exact formula.
Fan (convection) ovens run hotter
If your oven has a fan/convection setting, most UK recipes expect you to reduce the temperature by about 20°C (or roughly 25°F) from the conventional figure, or reduce by one gas mark. So a recipe calling for 180°C (gas mark 4) in a conventional oven would be set to around 160°C in a fan oven. Always check your oven’s manual — some manufacturers calibrate the fan setting differently, and the dial may already account for this.
Why this matters more than it seems
Oven temperature has an outsized effect on baking in particular. A cake baked 20°C too hot will often brown on the outside before the inside is cooked through; one baked 20°C too cool may never develop a proper crust or rise correctly. Because Celsius and Fahrenheit scales have different “step sizes” (each degree Celsius is 1.8 degrees Fahrenheit), a small misreading — say, reading “180” on a Fahrenheit-labeled dial when a recipe means 180°C — results in an oven that’s running more than 100°F too cold, which is enough to ruin most baked goods.
Quick sanity checks
If you’re ever unsure whether a number is in Celsius or Fahrenheit, a few reference points help:
- Room temperature is about 20°C / 68°F.
- Water boils at 100°C / 212°F.
- A “moderate” oven — the most common baking temperature — is around 180°C / 350°F.
- A “hot” oven for roasting or pizza is around 220–230°C / 425–450°F.
If a recipe’s oven temperature is below 100, it’s almost certainly Celsius (ovens don’t operate below boiling point in Fahrenheit for cooking). If it’s above 250, it’s almost certainly Fahrenheit. This quick check can catch a misread number before you preheat.
For the full table with fan oven adjustments and a quick lookup tool, see our oven temperature conversion chart.