Oven Temperature Conversion Calculator
Baking a recipe from a British cookbook? Your oven dial shows Gas Mark, but the recipe says 350°F? This calculator converts any oven temperature between Fahrenheit (°F), Celsius (°C), and Gas Mark in one step. It also flags the convection (fan) oven adjustment — convection ovens typically run 25°F (about 15°C) hotter than conventional ovens, so you should reduce the set temperature accordingly.
When to use this calculator
- Converting a US recipe temperature (°F) to a European oven dial (°C)
- Reading a British recipe that lists Gas Mark and finding the °F equivalent
- Adjusting a conventional oven recipe for a convection/fan oven
- Verifying a roasting temperature when switching between cookbook standards
- Teaching baking classes that reference multiple temperature scales
- Double-checking oven calibration against a known reference temperature
How it works
2 min readWhat is oven temperature conversion?
Oven temperature conversion is the process of translating cooking temperatures between Fahrenheit (°F), Celsius (°C), and Gas Mark scales. The standard formula is °C = (°F − 32) × 5/9. Convection ovens require a 25°F reduction for optimal results. Accurate conversion ensures recipes bake consistently regardless of oven type or regional measurement system.
How It Works
This calculator uses the standard thermometric formulas to convert between Fahrenheit, Celsius, and Gas Mark. All conversions pass through Celsius as the intermediate unit.
Formulas
// Fahrenheit → Celsius
°C = (°F − 32) × 5 / 9
// Celsius → Fahrenheit
°F = °C × 9 / 5 + 32
// Celsius → Gas Mark (approximate; valid 135°C – 290°C)
Gas Mark = (°C − 121) / 14
// Gas Mark → Celsius
°C = Gas Mark × 14 + 121The Gas Mark formula is a linearization of the traditional British scale. It aligns precisely at the canonical reference points (see table below).
Reference Table
| °F | °C | Gas Mark | Heat Description |
|---|---|---|---|
| 250 | 120 | ½ | Very Low |
| 275 | 135 | 1 | Very Low |
| 300 | 150 | 2 | Low |
| 325 | 165 | 3 | Moderately Low |
| 350 | 180 | 4 | Moderate |
| 375 | 190 | 5 | Moderately Hot |
| 400 | 200 | 6 | Hot |
| 425 | 220 | 7 | Hot |
| 450 | 230 | 8 | Very Hot |
| 475 | 245 | 9 | Very Hot |
| 500 | 260 | 10 | Extremely Hot |
Worked Example
You have a recipe that calls for Gas Mark 6.
1. Convert to °C: 6 × 14 + 121 = 205°C (rounded to 200°C by convention)
2. Convert to °F: 200 × 9/5 + 32 = 392°F (often listed as 400°F)
3. You are using a convection oven → reduce by 25°F → set to 375°F (190°C).
Convection / Fan Oven Adjustment
Convection ovens circulate hot air, making them roughly 25°F (14–15°C) more efficient than conventional ovens at the same dial setting. When a recipe is written for a conventional oven, reduce the temperature by 25°F (or ~15°C) if you are using convection. Alternatively, reduce baking time by about 20–25% at the same temperature.
Limitations
Frequently asked questions
What is the most common baking temperature in both °F and °C?
350°F / 180°C (Gas Mark 4) is by far the most common baking temperature in English-language recipes. It is considered a 'moderate' oven and suits most cakes, cookies, and casseroles.
How do I convert Gas Mark to Fahrenheit manually?
Multiply the Gas Mark number by 25 and add 250°F as a quick rule. For example, Gas Mark 4 → 4 × 25 + 250 = 350°F. The precise formula is °C = Gas Mark × 14 + 121, then convert °C to °F.
Should I always reduce temperature for a convection oven?
Yes, if the recipe was written for a conventional oven. The standard adjustment is 25°F (about 15°C) lower, or you can keep the same temperature but reduce baking time by 20–25%. Check for doneness a few minutes early.
Why does Gas Mark use fractions like ¼ or ½?
Gas Mark fractions represent very low temperatures used for slow cooking or warming. Gas Mark ¼ ≈ 107°C (225°F) and Gas Mark ½ ≈ 120°C (250°F). These settings are common in British slow-roast and meringue recipes.
Is 180°C the same as 180°F?
No. 180°C = 356°F, which is close to the standard moderate baking temperature of 350°F. 180°F = 82°C, which is far too low for baking — it is closer to a water bath or sous-vide temperature.
How accurate is the Gas Mark conversion formula?
The linear formula matches the official Gas Mark scale within ±5°C across the practical cooking range (Gas Mark ½ to 9). It is accurate enough for all domestic baking; minor discrepancies between brands of cookers are larger than formula error.
What temperature is considered 'very hot' for roasting?
450–475°F (230–245°C, Gas Mark 8–9) is generally described as 'very hot' and is used for searing, high-heat roasting, pizza, and bread with a crisp crust.
My recipe says 'moderate oven' but gives no number. What temperature should I use?
A 'moderate' oven is 350°F (180°C, Gas Mark 4). 'Low' is around 300°F (150°C), 'moderately hot' is 375°F (190°C), and 'hot' is 400–425°F (200–220°C).
Does altitude affect oven temperature conversion?
No, the conversion math is the same at any altitude. However, at high altitudes (above 3,500 ft / 1,070 m), baked goods may require slightly higher temperatures or longer bake times because of lower air pressure. That is a separate adjustment from unit conversion.