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Oven Temperature Conversion Calculator

Convert conventional to convection oven temperature with automatic 20C reduction.
Also converts between Fahrenheit, Celsius, and UK Gas Mark for any recipe.

Converted Temperature

Oven temperature conversion is essential when following recipes from different countries, since the US uses Fahrenheit, most of Europe uses Celsius, and UK/Australian recipes often specify Gas Mark. All three scales describe the same physical temperature, just expressed differently.

Fahrenheit ↔ Celsius formula: °C = (°F − 32) × 5 ÷ 9 °F = (°C × 9 ÷ 5) + 32

Gas Mark conversion: Gas Mark = (°F − 121) ÷ 25 (approximate) Or use the standard reference table below.

Where:

  • °F — Fahrenheit; used in the United States; water freezes at 32°F, boils at 212°F
  • °C — Celsius/Centigrade; used in most of the world; water freezes at 0°C, boils at 100°C
  • Gas Mark — a UK/Irish/Australian system for gas ovens numbered 1/4 through 10; Gas Mark 1 = 275°F (135°C)

What each variable means:

  • The −32 step — shifts the Fahrenheit zero point to align with Celsius zero
  • The 5/9 ratio — the conversion factor between the size of each degree; 1°C = 1.8°F
  • Gas Mark — an empirical scale; each mark represents 25°F increment from Gas Mark 1 (275°F) through Gas Mark 9 (475°F); Gas Mark 10 = 500°F+

Reference: standard oven temperature table:

°F °C Gas Mark Description
250 120 ½ Very low
275 135 1 Very low
300 150 2 Low
325 163 3 Moderate-low
350 177 4 Moderate
375 190 5 Moderate-high
400 200 6 Hot
425 220 7 Hot
450 230 8 Very hot
475 245 9 Very hot

Worked example 1: British recipe says “Gas Mark 6.” Convert to Fahrenheit and Celsius for a US oven.

  • Gas Mark 6 = 400°F = 200°C (standard hot roasting temperature)

Worked example 2: US recipe says “Bake at 350°F.” Convert for a European oven.

  • °C = (350 − 32) × 5 ÷ 9 = 318 × 0.5556 = 176.7°C → round to 175°C or 180°C
  • Gas Mark = (350 − 121) ÷ 25 = 229 ÷ 25 ≈ Gas Mark 4

Fan/convection ovens run hotter — reduce stated temperature by 20°C (35°F) when using fan mode.


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