Recipes from different countries describe oven heat in different systems — Celsius, Fahrenheit, or the UK's gas mark scale — and getting the conversion wrong is one of the most common reasons a bake comes out under or overdone. Here's a full reference table and the reasoning behind it.
The Three Systems
Fahrenheit is standard in the US, Celsius is standard almost everywhere else, and gas mark is a UK-specific scale historically tied to gas ovens, running from ¼ up to 9. None of these convert with a clean round-number formula between all three, which is why a reference table is more useful in the kitchen than mental math.
Conversion Table
| °C | °F | Gas Mark | Description |
|---|---|---|---|
| 110°C | 225°F | ¼ | Very low / warming |
| 130°C | 250°F | ½ | Very low |
| 140°C | 275°F | 1 | Low |
| 150°C | 300°F | 2 | Low |
| 160°C | 325°F | 3 | Moderately low |
| 180°C | 350°F | 4 | Moderate |
| 190°C | 375°F | 5 | Moderately hot |
| 200°C | 400°F | 6 | Hot |
| 220°C | 425°F | 7 | Hot |
| 230°C | 450°F | 8 | Very hot |
| 240°C | 475°F | 9 | Very hot |
The Formula (When You Need an Exact Number)
To convert Celsius to Fahrenheit exactly: multiply by 9/5 and add 32. So 180°C × 1.8 = 324, + 32 = 356°F — which is why cookbooks round it to the nearer "clean" oven dial number, 350°F, rather than using the decimal-precise figure. Gas marks don't have a formula at all; they're a fixed lookup table set by convention, which is the real reason a reference table beats mental math for this particular conversion.
Why Oven Conversions Are Approximate
Even with a correct conversion, ovens themselves vary — a domestic oven can run 10-15°C hotter or cooler than its dial suggests, fan (convection) ovens typically need to be set about 20°C lower than a conventional recipe specifies, and oven thermometers are the only reliable way to know what's actually happening inside. Treat the table above as your starting point, not a guarantee.
Fan (Convection) Oven Adjustment
| Conventional | Fan/Convection |
|---|---|
| 160°C / 325°F | 140°C / 285°F |
| 180°C / 350°F | 160°C / 325°F |
| 200°C / 400°F | 180°C / 350°F |
| 220°C / 425°F | 200°C / 400°F |
FAQ
Is gas mark 4 the same as 180°C everywhere?
By convention, yes — gas mark is standardized to specific Celsius/Fahrenheit
values regardless of oven brand.
Do I need to adjust baking time as well as temperature for a fan oven?
Usually you adjust temperature only and keep the time roughly the same, checking
a few minutes early since fan ovens can cook faster.
What if my oven doesn't show gas marks or Celsius?
Use the table's Fahrenheit column directly, or convert on the fly with
the conversion tool.
Once your oven's set correctly, you'll also want your ingredient weights right — see cups to grams conversions, or open the tool to convert both in one place.