Why does Ebay shipping calculator change dimensions and weights at will?

[textbookguy]

I am constantly shocked when I go to print out a shipping label and see what I consider too little shipping charged. For example,e I recently sold two headlights and the package was 24 x 24 x 13 and 15 lbs. Each light Assembly weighs about 3 lbs so Ebay got the dimensions correct but changed the weight to 6 lbs. I did not catch it and now I am concerned that when this ships I am going to get slammed for FedEx up-charges. This is not the first time this has happened, it seems to happen about 25-30% of the time. 

[fern*wood]

I looked at your listing for the two headlights and saw you put into the description that the postage was for one and to double it for both.  You have to enter the correct dims/weight in the shipping section when you list in order for the buyer to pay the correct amount.   Since the listing was for both, I don’t understand why you would only enter info for one.

[statesmen2000]

This has happened to me multiple times.  As I am creating a listing, I type in the dimensions and weight of the item I am selling, click 'save draft'. I then resume draft in order to add photos to the draft and the dimensions and weight have reverted back to what it says before I edited the draft.  And EBAY's suggested weight/dimensions are WAY off from the item I am selling.