Published July 28, 2026
Oven Temperature Conversion Guide: F, C, and Gas Mark
Recipe from a UK cookbook calling for "Gas Mark 6"? American recipe listing 375°F but your oven is calibrated in Celsius? Oven temperature conversion trips up more home cooks than almost any other measurement mismatch, mostly because there are three different systems in common use around the world, and none of them line up in obvious, round numbers.
The three systems
Fahrenheit (°F) is the standard in the United States. Celsius (°C) is used almost everywhere else, including the UK (alongside Gas Mark), Europe, Australia, and most of Asia. Gas Mark is a UK-specific numbering system historically used on gas ovens, running from a low of 1/4 up to 9, and it's still commonly listed in British recipes and cookbooks even on modern electric ovens.
Quick reference table
| Fahrenheit | Celsius | Gas Mark | Common use |
|---|---|---|---|
| 225°F | 107°C | 1/4 | Very low / warming |
| 250°F | 121°C | 1/2 | Very low / slow cooking |
| 275°F | 135°C | 1 | Low |
| 300°F | 149°C | 2 | Low |
| 325°F | 163°C | 3 | Moderate / slow roasting |
| 350°F | 177°C | 4 | Standard baking |
| 375°F | 191°C | 5 | Moderate-hot |
| 400°F | 204°C | 6 | Hot / roasting |
| 425°F | 218°C | 7 | Hot |
| 450°F | 232°C | 8 | Very hot |
| 475°F | 246°C | 9 | Very hot / pizza, bread |
The math behind the conversion
Converting between Fahrenheit and Celsius uses a fixed formula: °C = (°F − 32) × 5/9, and the reverse is °F = °C × 9/5 + 32. Gas Mark doesn't have a clean mathematical formula tying it to Celsius — it's a standardized lookup table rather than a linear conversion, which is why most gas mark conversions are done by matching to the nearest standard value rather than by calculation. Our oven temperature converter handles all three directions automatically, including snapping to the nearest standard Gas Mark when converting from Fahrenheit or Celsius.
Why oven calibration matters just as much as conversion
Even a perfectly converted temperature can produce inconsistent results if your oven itself isn't well calibrated. Home ovens are notorious for running 15-25°F (about 8-14°C) hotter or cooler than their display suggests, and that's before accounting for hot spots, how long the oven took to preheat, or whether you opened the door mid-bake. An inexpensive oven thermometer placed inside your oven is one of the highest-value tools a home baker can own — it tells you what temperature your food is actually experiencing, not just what the dial claims.
This matters especially when working from a converted temperature. If a recipe calls for Gas Mark 4 (177°C / 350°F) and your oven runs 20°F hot, you're effectively baking at closer to Gas Mark 5 without realizing it — enough to noticeably affect browning and bake time on delicate items like cakes and pastries.
Practical tips for working across systems
- When following a recipe from a different country, always convert the temperature before you start preheating — don't estimate on the fly.
- Fan/convection ovens typically run about 20°F (10°C) hotter than conventional ovens at the same setting; many UK recipes note this explicitly for Gas Mark conversions.
- If a converted temperature lands between two Gas Marks, round to the nearest standard mark rather than trying to set a fraction your oven dial doesn't support.
- Keep a printed or bookmarked conversion reference in the kitchen — trying to do this math with wet or floury hands is its own hazard.
The takeaway
Fahrenheit, Celsius, and Gas Mark are just three different scales describing the same underlying oven temperature. Once you have a reliable conversion (and a thermometer to confirm your oven is telling the truth), following recipes from anywhere in the world becomes far less error-prone.