I just found a serious problem with the way Amazon is calculating the FBA size tier. It has to do with the order the dimensions are entered. If the thickness is not last then a 6x9x.6 book that is entered as 6x.6x9 is classified as a large item rather than small. The FBA fee increases from 2.41 to 4.18. Check ASIN 0300066422.
I have already found 14 of my skus that are not classified correctly out of about 30 I manually checked. I have thousands of sku’s in inventory. That means I could lose $1.77 on many sales. Think of the extra revenue that Amazon is receiving because of this programming error.
I am posting to let other sellers know to start checking your smaller media items to make sure the FBA fees are calculated correctly.