A few years ago, I heard someone had made a cotton potato bag to use in the microwave, so my search brought me to YouTube and hence my potato bags were born. ;-)
The dimensions I used for the single potato bag are 5.5” X 16.5” and I used 1/4” seams. If I made another one I would make it 6.5” wide rather than 5.5”. I used leftover fabric from the bigger one I made and that is all I had. (I like using the smaller one to bring with me for an all day outing when a lunch is brought along and a microwave is available.)
It is made with 100% cotton fabric and batting.
The bigger one is 11” X 24”.
Here is the link to the YouTube video I found for the instructions.