Changing the Pan size in Baking
i have a cake recipe that calls for 2 10" round pans....what size rectangular pan can i substitute instead of the rounds. thanks for your help. petra
It would depend on what type of cake it is. It would not work for a sponge type cake (whipped egg yolks with sugar, fold in flour and leavening, then beaten egg whites) or genoise. If it is a butter cake (creaming the butter with sugar, add the eggs, alternately mixing in liquid and dry ingredients), at least a 9x13 or preferably a little larger. Give it an extra 5 to 10 minutes baking time.
Since you whip the eggs until very light and pale, I assume you are making a sponge cake. This type of cake is very delicate and airy. If you bake in it one large pan, there is not enough structure to support the cake and the middle will collapse when you take it out of the oven. You can make sponge cake sheets but they are generally very thin. The proportion of ingredients and baking time of sponge sheets are different than for round sponge cakes. You should be able to find a good sponge sheet in any good baking book. Depends on your finished cake, a thin sponge sheet might not work for you.
There are many web sites that give pan conversion info - start at google (pantry_substitutes_pansizes1)
You can calculate it yourself. A 10-inch round pan has a surface area of 5*5*3.14, about 78 square inches.
A 9x13 rectangular pan would be 117 square inches, about as much as 1.5 10-inch round pans, so something a bit larger would probably be better.
The Cake Bible is my go-to for conversion information.
A 10" round's volume is 10 3/4 cups. As Hal calculated, a 9x13" holds 15 cups, about 1.5 the volume of the 10" round. But the other really useful bit of info: a round pan is 3/4 the volume of a square pan. So to determine the volume of a square pan, you can multiply the volume of the round pan by 1.33.
So using the Cake Bible's volume chart, here's what you get:
8" round volume = 7 cups
7 cups x 1.33 = 9.31 cups volume in 8" square.
9" round volume = 8 2/3 cups
8 2/3 cups x 1.33 = 11.53 cups volume in 9" square.
So I think the 9" square will work okay.
Your cake recipe sounds like it's a sponge type. You can change the cake pan size, but to get the same height as you would have gotten in the two 10" pans, you need an odd-sized rectangular pan, about 9" x 17", or 12" square, or 11" x 14" (whatever dimensions make up 157 sq. in.).
You could do as PBSF says and go with a 9" x 13" pan and bake it for longer.
What are you trying to make? Are you planning to make a rectangular cake to cut up into equal-sized layers?