how to convert recipes for different size pans

When we try a new recipe, we often make a smaller version of the original recipe. For cookies, that's as simple as cutting the ingredients in half and making a smaller quantity. But for cakes, it gets quite a bit more complicated. And - horrors - requires some math!

In this post, we explain how to adjust your recipes for the pans you have on hand or when you want to make a smaller cake or cheesecake because you're not feeding a large group. Thanks to Alice Medrich from Food 52  for these calculations!
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common pan sizes

 (with the numbers rounded up to the nearest inch):

AREA OF RECTANGULAR PANS

• 6 x 6 = 36 square inches
• 7 x 7 = 49 square inches
• 8 x 8 = 64 square inches
• 9 x 9 = 81 square inches
• 9 x 13 = 117 square inches
• 12 x 16 (half-sheet pan) = 192 square inches

AREA OF ROUND PANS

• 5 inch = 20 square inches
• 6 inch = 29 square inches
• 7 inch = 39 square inches
• 8 inch = 50 square inches
• 9 inch = 64 square inches
• 10 inch = 79 square inches
• 12 inch = 113 square inches

​HOW TO USE THESE NUMBERS:
Once you know the area of any pan, you can compare it to the area of another pan to see how much bigger or smaller it is. You can divide the area of a large pan by the area of a small pan to figure out how many times to multiply a recipe to fill the larger pan with the same depth of batter. In our case, we usually are dividing a larger recipe. So, for example, if we want to divide a recipe designed for a 9-inch round pan (64) and make it in a 6-inch round pan (29), we multiple each of the ingredients by .45 or 45% (29/64). In this case, we'd round up to 50 percent for ease of conversion - as long as the pan can accommodate the small increase in total ingredients. For such as small increase, it's not likely that the baking time would need to be increased for most recipes.

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how to do your own calculations

For squares and rectangles: The area of a square or rectangular pan is calculated by multiplying one side times the other side. The area of an 8-inch square is 64 square inches because 8 x 8 = 64; the area of a 9 x 13-inch pan is 117 square inches because 9 x 13 = 117. Easy. 

For rounds: The area of a circle equals π times the radius squared. In case you don’t remember, π = 3.14; the radius of a circle is half of its diameter; and squaring means multiplying a number by itself. Ready? To calculate the area of an 8-inch round pan, multiply 3.14 (π) by 4 (because it’s half of 8) times 4. Thus, the area of an 8-inch circle is 3.14 x 4 x 4, approximately 50 square inches. Not so hard!
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