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convert recipe from round pan to larger retangle pan?

I want to make a larger amount of the great Chow Jam Crostata recipe, using a 9 x 11 rectangle pan instead of the springform pan in the recipe. It's a great recipe that I've made a couple of times now, with very happy results. http://www.chow.com/recipes/11931-ita.... For complicated reasons, I can't simply double the recipe and use two springform pans.

I was once at a dinner with a bunch of female scientists who were talking about using Pi to turn a round-pan cake recipe into a square-pan recipe. Needless to say, I was unable to keep up with the conversation.

Normally, I would measure how much water each of the containers holds and make a rough approximation. But I would love it if someone would help me with the conversion here. I will cut the finished product into bars, like linzer bars.

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  1. An 11 1/4 inch round pan has the same area as a 9*11 rectangle, if that's what you are asking.

    This site has all manner of handy calculators.

    I think I understand what you are asking now. Multiply the quantities in the recipe by 1.25 and you should be fairly close. 99/78.5=1.26

    1. A knowledge of geometry would be helpful. Knowing the formulas for areas of a circle and a four-sided figure and then multiplying by depth of vessel. But what do I know, I was taught geometry in 1951 when I was in 10th grade.

      2 Replies
      1. re: ChiliDude

        No problem, geometry (my favorite subject) hasn't changed since you were in school. They've changed some of the processes but the basic formula you used in school still applies and it's taught in 8th and 9th grade these days. I guess kids are smarter earlier in life than we were.

      2. What is the diameter of the spring form pan? The area formula, as you see in the great calculator from kengk, is pi (call it 3.214) times the radius (assuming the spring from is 9 inch diameter, that would be 4.5) squared. So, assuming a 9 inch spring form, the area is about 65 square inches.

        The area for a rectangle is easier, which is 9X11 or 99 square inches. 65 square inches is about two thirds of 99. So, if you want the recipe to be the same depth, you would need to increase the recipe by around a third.

        If your spring form is a different diameter, you would need to do some more math.

        You might also have to adjust your baking times for the bigger area.

        7 Replies
          1. re: sr44

            Okay, so 5 X 5 X 3.214 = 81 square inches.

            9X11 = 99 square inches.

            If you want to make a 9X11 pan, you would need to increase ingredients by 11%. This might be tricky to calculate. Have you considered using a 9.5X13 inch pan? Then you would have to make half as much again. So, if it called for 1 cup of flour, you would use 1 1/2 cup, if 2 eggs, you would use 3, etc.

            I assume your goal is to make more, no? 11% is going to be a pain to calculate, and isn't really a very big increase. If the normal recipe fed 10 people, this increase would only feed 11. Hardly worth the trouble to make such a small increase.

            1. re: dkenworthy

              Your formula for "Pi" doesn't agree with mine. Where'd you come up with 3.412?

              1. re: todao

                oops, I made a dysgraphic. Of course, pi is 3.214.

                1. re: dkenworthy

                  No, it is not. Try 3.14. Off to look up dysgraphic. : )

                  1. re: kengk

                    omg, I can't believe I didn't look it up rather than rely on my faulty memory. Sorry!

          2. forget the complicated calculations. make a double batch of the dough, use what you need to fill the 9x11 pan, and use the remaining dough to make something else - perhaps a free-form crostata or miniature tarts.

            3 Replies
            1. re: goodhealthgourmet

              That is usually my take on things, but there are two reasons why I'm not doing it; 1) my waistline, and 2) the dough is very soft and needs the structure of a pan. But I suppose I could make a small one and freeze it . . . . .
              The great thing about this recipe is how very quickly it comes together, and yet the final product is not only attractive, but truly delicious.

              1. re: somervilleoldtimer

                you can just freeze the extra dough for future use if you don't want to have the added temptation of extra baked goods in the house.

                1. re: goodhealthgourmet

                  True. If I doubled it but only used 1.5 of the total, I could do the same next time I make it. Hmmm.