Oven Temperature Conversion Calculator

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 − 250) ÷ 25 Gas Mark 1 is 275°F and every mark after it adds 25°F, so the formula anchors on 250 rather than on the mark itself. Check it against the table below: 400°F gives (400 − 250) ÷ 25 = 6, and Gas Mark 6 is indeed 400°F.

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:

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 − 250) ÷ 25 = 100 ÷ 25 = Gas Mark 4

Fan and convection ovens

A fan moves air across the food, so the same dial setting cooks faster and browns harder. The standard correction is to drop the temperature by 25°F, or 15°C, and to start checking 10 to 15% earlier than the recipe says.

You will also see “reduce by 20°C” in British recipe writing, which is a slightly larger cut than 25°F. Both conventions are in use and neither is wrong; this calculator uses 25°F and 15°C so that the Fahrenheit and Celsius answers describe the same physical change. Ovens vary by more than the difference between the two rules, so an oven thermometer beats either.