Oven Temperature Converter

How it works

Fahrenheit and Celsius are linked by an exact linear formula. Water freezes at 32°F (0°C) and boils at 212°F (100°C) at sea level, so 180 Fahrenheit degrees span the same range as 100 Celsius degrees:

°C = (°F − 32) × 5 ÷ 9
°F = °C × 9 ÷ 5 + 32

Gas marks are not a unit of temperature but numbered steps on a gas oven's dial, dating from early 20th-century British gas cookers and still printed in U.K. and Irish recipes. Published conversion tables, including those from BBC Good Food and Which?, space the numbered marks 25°F apart starting at 275°F for gas mark 1, with two cooler fractional marks below it:

gas mark ¼ = 225°F, gas mark ½ = 250°F
gas mark n (1–10) = 250 + 25 × n °F

To go the other way, the calculator converts your temperature to Fahrenheit and picks the nearest mark. Settings below about 225°F or above about 500°F fall outside the gas mark scale.

Exact versus rounded temperatures

Recipes almost never print exact conversions. American 350°F is exactly 176.7°C, but U.K. recipes and tables call it 180°C; 400°F is 204.4°C but is printed as 200°C. That rounding is fine, because oven thermostats typically cycle several degrees above and below the set point anyway. The calculator shows the exact result to one decimal place and a whole-number value for setting the dial.

Exact Celsius values are calculated from each mark's Fahrenheit value. Rounded Celsius and fan columns follow BBC Good Food's table; tables from different publishers sometimes differ by 10°C at gas mark 3 (160 or 170°C), so treat these as close equivalents rather than precise values.

Fan and convection ovens

A fan (convection) oven blows hot air around the food. Moving air transfers heat faster than still air, so food browns and cooks more quickly at the same setting. Recipes written for conventional ovens therefore need a lower temperature in a fan oven. Two rules of thumb are widely published, and they are close to each other:

• U.S. guidance: King Arthur Baking advises reducing the temperature by 25°F and checking for doneness about 10 minutes earlier than the recipe says.
• U.K. guidance: BBC Good Food and appliance makers list fan temperatures 20°C below conventional — for example 180°C conventional becomes 160°C fan.

20°C is 36 Fahrenheit degrees, so the U.K. rule is a little more conservative than the U.S. one. The calculator shows both, rounded. Two important caveats: many modern ovens subtract the difference automatically when you choose convection mode, and many U.K. recipes already print a separate fan temperature. Check your oven manual and the recipe so you don't reduce twice. Delicate bakes such as soufflés, custards and some sponge cakes may do better with the fan off.

Getting the temperature right in your oven

The number on the dial is a target, not a guarantee. Oven thermostats can run 25°F or more hot or cold, and temperatures differ between the top, bottom and back of the cavity. An inexpensive oven thermometer placed in the center of the rack tells you what your oven actually does. If it runs hot, set the dial lower; if it runs cool, set it higher. Preheat fully — many ovens signal "ready" before the walls and racks are hot — and avoid opening the door repeatedly, which can drop the air temperature sharply.

Dark metal pans absorb more heat than shiny ones and can brown the base faster; glass and ceramic dishes heat slowly but hold heat longer. Some bakers lower the temperature by about 25°F when switching to dark or glass pans for this reason.

Oven temperature and food safety

Oven temperature controls how fast food cooks, but safety depends on the temperature inside the food, measured with a food thermometer. USDA's Food Safety and Inspection Service publishes these safe minimum internal temperatures:

See the full FSIS Safe Minimum Internal Temperature Chart for more foods. Converting the oven setting correctly helps food cook evenly; a thermometer confirms it is done.

Worked examples

Example 1: 350°F to Celsius and gas mark

(350 − 32) × 5 ÷ 9 = 176.7°C, printed in U.K. recipes as 180°C. Nearest gas mark: (350 − 250) ÷ 25 = gas mark 4. Fan setting: about 325°F (US rule) or 157°C → 160°C (UK rule).

Example 2: 200°C to Fahrenheit

200 × 9 ÷ 5 + 32 = 392°F, usually set as 400°F (gas mark 6). In a fan oven, about 180°C.

Example 3: Gas mark 7 to °F and °C

250 + 25 × 7 = 425°F; (425 − 32) × 5 ÷ 9 = 218.3°C, printed as 220°C.

Example 4: A convection recipe in a conventional oven

A recipe written for 160°C fan needs about 180°C (356°F) in an oven without a fan.

Limitations

• Gas marks are dial steps, and the temperatures they produce vary between ovens and manufacturers.
• Fan adjustments (−25°F or −20°C) are rules of thumb; follow your oven manual where it differs.
• Altitude, pan material, oven calibration and how full the oven is all affect results.
• Air fryers and combination steam ovens are outside the scope of these conversions.

Who should not rely on this calculator

This converter is for oven settings only. Don't use oven temperature to judge whether meat, poultry, eggs or leftovers are safe to eat — use a food thermometer and USDA FSIS safe minimum internal temperatures. People who are pregnant, older, immunocompromised or cooking for young children should be especially careful with food-safety temperatures.