Why is it that when I print out an address label for a book the $ amount is always way off?

Today I printed the label for one book. It printed it out as First Class $1.30

When I get to the post office they always look at me as if I am crazy when the see the postage amount.

It cost me $2.15  to mail this book first class.

Just tired of explaining to the post office officials that I know the price printed is wrong.

The weight is estimated and that determines the postage cost. To get an accurate cost you should weigh the book before printing the wrapper and correct the book weight.

The type of packaging you use will also really make a difference, especially for smaller books.  Heavy mailers can double the weight of a small book.

I've started to mark out the recommended postage amount when taking it to the post office. 

It seems to make the transaction more complicated. Sometimes they ask if it is prepaid postage. Other times they want to discuss that it's not correct. 

Laura- I thought that might be it, but this book was in plastic wrap and the paper label mailer.

Bridget- That's a good idea, it does make the transaction more complicated.

I get that the postage is an estimate but most of mine have been WAY off. $1.30 for most regular size paperbacks first class? Crazy....

Just adjust the weight - put in 8 ounces or more.

We generally check the postage ourselves, but a couple of days ago we were in a rush.  I wrapped my husband's 2 tiny paperbacks in plastic and stuck on just the label portion of the printed page...not even an ounce of extra weight.  I put the amount that printed out on each.  They were both returned today with postage due. 

Not complaining...I really did know better.  Just sharing another reason to check the postage yourself or at the PO.

I've noticed since they went to the new system, the postage is way off too.  The old system was very accurate, at least in my experience so this is a new problem I'm finding.  My packaging has not changed.

I weigh the naked book before printing postage, then add .7 to allow for the saran wrap, two sheets of paper and packing tape.  You definitely have to double check the weight though!

I always bring my books to the post office since I have to pick up my mail there anyway. I've just been surprised at how far off the postage has been recently. Dollars off, not just sense. Of course it's not a big deal, but as Lynda noted it does seem recent that the postage has been so far off. 

I think the postal employees try to over explain to me that the postage printed is not correct as if they are afraid I'll argue with them! I just jump right in and tell them I know it's way off.