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    Home > Baking Information

    Published: Sep 9, 2013 · Modified: Jan 19, 2025 by Helen S Fletcher · This post may contain affiliate links · 18 Comments

    Pan Size Conversions

    Pan Size Conversions

    Pan size conversion is one of the most confusing elements of baking whether it is substituting square pans for round pans or for the same shape pans in smaller or larger size.

    The easiest way to convert the amount of batter is to use square inches so long as the depth of the pans are the same.

    You will notice that square pans of the same size cannot be substituted for round ones if you wish the layers to be the same depth.  When converting from round to square pans it takes approximately ⅓ more batter for the square ones.

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    If you are going from a 2” to a 3” pan of the same shape, increase the amount by ⅓.

    When you are changing the size, the temperature of the oven remains the same but the time may need to be adjusted up or down depending upon the thickness of the layers.

    In my recipes, I give the weights of the finished batter as well as how much should go in each pan.  For instance, if a base layer weighs 750 grams or 26 ounces, it can easily be divided into different size layers.   This allows you to use a base recipe with different fillings requiring a different number of layers without recalculating each time, making pan size conversions very easy.  Using the 750 grams you could make:

    2 - 9” layers at 375 grams or 13 ounces each
    3 - 9” layers at 250 grams each or 9 ounces each
    4 - 9” layers at 185 grams each or 6 ½ ounces each

    CALCULATING SQUARE INCHES FOR SQUARE OR RECTANGULAR PANS:    For the square pan, multiply two sides of the pan.  For instance for an 8 inch square pan, multiply 8x8 = 64 square inches.  For a rectangle, simply take the measurements of the long side and the short side of a rectangular one and multiply  them, i.e. 9x13=117 square inches.

    8” = 64 square inches
    9” = 81 square inches
    10” =100 square inches
    12” =144 square inches
    14” = 195 square inches
    16” = 256 square inches
    18” = 325 square inches
    20” = 400 square inches
    9”x13” pan – 9x13” = 117 square inches
    Quarter sheet pan - 9x13" =117 square inches
    Jelly Roll Pan - 10x15" - 150 square inches
    Half sheet pan - 18x13" = 234 square inches
    Full sheet pan - 18x26" = 468 square inches

    From this you can see that you can substitute two 8” pans for the 9”x13” one as  2x64 = 128 square inches which is close enough.

    CALCULATING SQUARE INCHES FOR ROUND PANS is a little more complicated.

    The formula is:  Divide the diameter of the pan in half to obtain the radius.  The radius is simply ½ the size of the pan.  Multiply that number by itself and then multiply that number by pi which is 3.14.

    For instance, the radius of a 9” pan is 4.5 inches.

    4.5x4.5 = 20.25 inches.
    20.25x3.14 = 63.58 which would round off to 64 square inches.

    8” = 50 square inches
    9” = 64 square inches
    10” = 79 square inches
    12” = 114 square inches
    14” = 154 square inches
    16” = 201 square inches
    18” =  254 square inches
    20” = 314 square inches

    You can see from these measurements, that the batter for a 9" square pan would make one 10" round one.  The numbers will not be exact, but as long as they are close they will be fine.

    A SECOND WAY to determine pan size is to measure the amount in a pan by cups. I have never used this method as weights are more exact and so much easier.

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    1. Cheryl says

      January 19, 2025 at 11:54 am

      I have a recipe that calls for a jelly roll pan. My pans are half sheet pans. What would the conversion be?
      Thank You,
      Cheryl

      Reply
      • Helen S Fletcher says

        January 19, 2025 at 12:18 pm

        Hi Cheryl - A jelly roll pan is slightly smaller than a half sheet pan. It is 10x15" or 150 square inches whereas a Half sheet pan is 18x13" or 234 square inches. So your calculation would be 2/3 of the half sheet would be 154 square inches. Hope this helps.

        Reply
    2. RD says

      October 03, 2024 at 2:56 pm

      A friend of mine who does a lot of baking swears that square pans hold more batter than their equivalent size round pans. I make pound cakes, and tend to use only 12-Cup capacity pans. Nordic Ware has a great SQUARE pound cake/bundt pan, but it's only 10-Cup capacity. My question is, will all the batter I usually put in my 12-Cup pans fit and come out fine if I buy and use the Nordic Ware, 10-Cup square pan?

      Reply
      • Helen S Fletcher says

        October 03, 2024 at 6:29 pm

        Your friend is correct. I talk about this in the Pan Size Conversions. If you place a 9" round pan in a 9" square pan you can see the square pan requires more batter to fill the corners. If going from a recipe that requires a 9" round pan to a 9" square pan I generally increase the recipe by 1/3 to fill in those corners. Just increase the recipe as noted and it will be fine.

        Reply
    3. Dawn says

      September 13, 2024 at 5:07 am

      I need to roll a 8-1/2 inch bread but would like rise it in a 8x8 to make easier to roll into a log it would rectangle already to make it easier. Sorry to bother you but thanks

      Reply
      • Helen S Fletcher says

        September 13, 2024 at 3:16 pm

        Hi Dawn, you are never a bother. Happy it worked out for you.

        Reply
    4. Kristen D Harvey says

      July 27, 2024 at 11:57 pm

      I need to double a recipe that would have fit in a 13x9-in pan approximately 2 and 1/2 in deep, into a 21x13 pan And somewhere between 2 and 1/2 to 3 in deep.

      What would be my cooking time differential? I'm looking to make a peach cobbler!

      Reply
      • Helen S Fletcher says

        July 28, 2024 at 4:50 am

        Hi Kristen - Since the depth is about the same, go with the original baking time and increase as needed.

        Reply
    5. Chip says

      May 07, 2023 at 6:59 pm

      Thanks so much for this work. Math is above my pay grade. You have a new follower!

      Reply
      • Helen S Fletcher says

        May 07, 2023 at 8:29 pm

        Hi Chip - Transparency demands that I let you know I had to ask my brother, an aeronautical engineer for a bit of help with the cubic inches. We had tons of engineers in the family and all I could ever do is add, subtract, multiply and divide. Sure I was a disappoint when it came to math! Welcome aboard.

        Reply
        • Debra says

          June 15, 2023 at 1:50 pm

          Not from what I see you have some awesome stuff and I appreciate your website I am joining the rest.

          Reply
          • Helen S Fletcher says

            June 15, 2023 at 3:50 pm

            Thank you Debra. I am happy to have you join us.

            Reply
    6. Mary Soucy says

      September 09, 2013 at 1:16 pm

      As always you are a wealth of information. I always look forward to your posts in my email! :)

      At your suggestion, I would love any tutorials you can put together on baking breads -- maybe French or Italian -- but totally your choice. Breads are about my favorite things to bake. I am always looking for tips and recipes from a pro.

      Thank you for all your efforts!

      Reply
      • hfletcher says

        September 09, 2013 at 2:56 pm

        Hi Mary: How apropos you should suggest bread. I have always loved baking bread also, and I am working on a post regarding yeast. If I finish it for next Monday, then a bread will appear on Thursday. Thanks for the suggestion.

        Reply
        • Mary Soucy says

          September 10, 2013 at 1:29 pm

          Yeah! Thank you!!

          Reply
          • hfletcher says

            September 10, 2013 at 1:44 pm

            You are welcome. My pleasure.

            Reply
    7. vera parker says

      September 09, 2013 at 11:34 am

      That was so helpful. Thank you.

      Reply
      • hfletcher says

        September 09, 2013 at 12:09 pm

        You're welcome.

        Reply

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