Oven temperature and pan size converter

How to convert oven temperatures

Use °C = (°F − 32) × 5/9 and °F = °C × 9/5 + 32. So 400 °F is 204.4 °C, which conversion tables round to 200 °C: gas mark 6, or 180 °C in a fan oven. In the other direction, 180 °C is 356 °F, usually written 350 °F.

Oven temperature conversion chart

Gas marks rise in steps of 25 °F from mark 1 at 275 °F. Each line gives the exact Celsius value, then the rounded conventional and fan settings from the Which? conversion table.

• Gas 1: 275 °F = 135 °C, written 140 °C (fan 120 °C)
• Gas 2: 300 °F = 148.9 °C, written 150 °C (fan 130 °C)
• Gas 3: 325 °F = 162.8 °C, written 160 °C (fan 140 °C)
• Gas 4: 350 °F = 176.7 °C, written 180 °C (fan 160 °C)
• Gas 5: 375 °F = 190.6 °C, written 190 °C (fan 170 °C)
• Gas 6: 400 °F = 204.4 °C, written 200 °C (fan 180 °C)
• Gas 7: 425 °F = 218.3 °C, written 220 °C (fan 200 °C)
• Gas 8: 450 °F = 232.2 °C, written 230 °C (fan 210 °C)
• Gas 9: 475 °F = 246.1 °C, written 240 °C (fan 220 °C)

Below mark 1, gas ½ is 250 °F (121.1 °C) and gas ¼ is 225 °F (107.2 °C). At the top of the scale, gas 10 is 500 °F (260 °C).

Fan and convection ovens

A fan oven moves hot air over the food, and at an unchanged setting it can cook the outside too quickly. Which? puts the fan setting about 20 °C below the conventional one, the rule used here: 180 °C becomes 160 °C fan.

Whirlpool's oven guidance instead suggests lowering a convection oven by 25 °F, about 14 °C, and points to the oven's manual. The manual for your model is the better guide.

Some ovens lower the temperature themselves on the convection setting. On those, set the recipe's conventional temperature; subtracting 20 °C as well lowers it twice.

How to adjust a recipe for a different pan size

Multiply every ingredient by the new pan's area divided by the recipe pan's area, which keeps the batter at the same depth. A 9 × 13 recipe (117 sq in) baked in an 8-inch square pan (64 sq in) needs 64 ÷ 117 = 0.547 of each ingredient.

Round pan area is π × diameter² ÷ 4, a square is side², and a rectangle is length × width. Areas of common pans:

• 6-inch round: 28.3 sq in
• 8-inch round: 50.3 sq in
• 9-inch round: 63.6 sq in
• 10-inch round: 78.5 sq in
• 8-inch square: 64 sq in
• 9-inch square: 81 sq in
• 9 × 13 rectangle: 117 sq in

Area grows with the square of the width. One more inch on an 8-inch round or square pan adds 26.6% more area, and a 10-inch round holds 23.5% more than a 9-inch round.

A 9 × 13 recipe can also go into two 9-inch rounds (127.2 sq in together), with layers about 8% thinner. Two 8-inch rounds (100.5 sq in) make the layers about 16% deeper.

Pan size examples

Round to square compares a 9-inch round with an 8-inch square, and metric round pans compares 20 cm and 23 cm diameters. The rectangle rows pair a 9 × 13 pan with an 8-inch square; equal square pans uses two 8-inch squares.

Every area is in square inches. Swapping the two pans gives the reciprocal multiplier: 0.547009 one way and 1.828125 the other.

What to enter

• Fan °C when a recipe or dial gives a fan-oven temperature; adding 20 °C converts it to conventional.
• Gas mark as ¼, ½ or a whole mark from 1 to 10. In-between marks such as 1.5 are not on the scale.
• Round pans by diameter, not radius, measured inside the rim. Each pan can be in inches or centimeters.

Common mistakes

• Reading a Celsius recipe as Fahrenheit. 180 °F is 82.2 °C, far too cool to bake. A European recipe's 180 means 180 °C, or 356 °F.
• Converting the fan offset as a temperature. A 20 °C difference is a 36 °F difference, because differences use only the 9/5 factor. Converting 20 °C as a reading gives 68 °F, which does not apply.
• Scaling by diameter instead of area. A 23 cm tin is 15% wider than a 20 cm tin but needs (23 ÷ 20)² = 1.3225, or 32.25% more batter.
• Entering the radius. Half the diameter gives a quarter of the area.
• Ignoring pan material. Metal, glass and ceramic pans heat differently even at the same size; King Arthur Baking's pan guide covers those differences.

Use the recipe scaler to multiply every ingredient by the pan factor. For single temperature conversions, the Celsius to Fahrenheit converter and the Fahrenheit to Celsius converter show the working.