Oven Temperature Conversion: Celsius, Fahrenheit & Gas Marks
Convert oven temperatures between Celsius, Fahrenheit and Gas Marks. Includes fan oven adjustments.
Oven temperatures in recipes vary by region — Americans use Fahrenheit, most of the world uses Celsius, and older British recipes use Gas Marks. This guide covers all the conversions you need, plus fan oven adjustments.
Complete Temperature Conversion Chart
The most common oven temperatures:
- 110°C = 225°F = Gas Mark 1/4: Very cool (meringues, drying)
- 120°C = 250°F = Gas Mark 1/2: Very cool
- 140°C = 275°F = Gas Mark 1: Cool (slow roasting)
- 150°C = 300°F = Gas Mark 2: Cool/slow
- 160°C = 325°F = Gas Mark 3: Moderately cool
- 180°C = 350°F = Gas Mark 4: Moderate (standard baking)
- 190°C = 375°F = Gas Mark 5: Moderately hot
- 200°C = 400°F = Gas Mark 6: Hot (roasting)
- 220°C = 425°F = Gas Mark 7: Hot
- 230°C = 450°F = Gas Mark 8: Very hot (pizza, bread)
- 240°C = 475°F = Gas Mark 9: Very hot
The Conversion Formula
To convert between Celsius and Fahrenheit:
- Celsius to Fahrenheit: (°C × 9/5) + 32 = °F
- Fahrenheit to Celsius: (°F - 32) × 5/9 = °C
For quick mental math, double the Celsius and add 30 for an approximate Fahrenheit temperature. Example: 200°C → 400 + 30 = 430°F (actual: 392°F).
Fan Oven Adjustments
Fan (convection) ovens circulate hot air, cooking faster and more evenly. Adjust temperatures:
- Standard rule: Reduce by 20°C (35°F) when using fan
- Or reduce time: Keep temperature, but check 5-10 minutes early
Examples of fan oven conversions:
- 180°C conventional = 160°C fan
- 200°C conventional = 180°C fan
- 350°F conventional = 325°F fan
- 400°F conventional = 375°F fan
Understanding Gas Marks
Gas Marks are a British system from the mid-20th century when gas ovens became common. The scale runs from 1/4 (lowest) to 10 (highest):
- Each Gas Mark represents roughly 14°C (25°F) increments
- Gas Mark 4 (180°C/350°F) is the standard "moderate" setting
- Modern gas ovens often show both Gas Marks and Celsius
Common Recipe Temperatures
Standard temperatures for different foods:
- Cakes: 160-180°C / 325-350°F / Gas 3-4
- Biscuits/Cookies: 180°C / 350°F / Gas 4
- Bread: 200-230°C / 400-450°F / Gas 6-8
- Roast chicken: 200°C / 400°F / Gas 6
- Roast beef (medium): 180°C / 350°F / Gas 4
- Pizza: 220-250°C / 425-475°F / Gas 7-9
- Meringues: 100-120°C / 200-250°F / Gas 1/4-1/2
- Pastry (blind bake): 200°C / 400°F / Gas 6
Calibrating Your Oven
Many ovens run hot or cold. To check yours:
- Buy an oven thermometer (inexpensive and essential)
- Place in the centre of the oven
- Preheat to 180°C/350°F
- Check if the thermometer matches the setting
- Note any difference and adjust recipes accordingly
A 10-15°C variance is common. A 25°C+ difference might warrant repair.
Hot Spots and Positioning
Temperature varies within your oven:
- Back: Usually hotter than front
- Top: Hotter for browning
- Bottom: Direct heat for crispy bases
- Centre: Most even temperature
For even baking, rotate trays halfway through cooking time.
Preheating Matters
- Always preheat: 15-20 minutes for most ovens
- Don't trust the beep: Many ovens signal before truly reaching temperature
- Exception: Slow-roasting can start from cold
- Pizza stones: Need 30+ minutes to fully heat
Altitude Adjustments
At high altitudes (above 1,000m / 3,000ft), air pressure affects baking:
- Increase oven temperature by 15-25°F (8-15°C)
- Reduce baking time slightly
- Baked goods rise faster and can over-expand
This primarily affects baked goods with leavening agents.