I just went to ship a small hardcover.  PBS estimated the shipping weight as over NINE POUNDS (9lbs, 5 oz).  Whiche would have cost nearly $7.  Actual shipping weight including packing (padded envelope plus tape plus label) was 11 oz!  That's a BIG discrepancy.  Anyone else come across this?

I've had some that were off enough, as they were small mass-market paperbacks that came up as large ones needing to be taken to the P.O. I also have some come up as Media Mail when 1st class is cheaper. I take all mine to the PO anyway, and the $2.53 Media rate covers a lot of books. Ideally, I like to think when people get books where the postage cost was way off, it helps correct it for the next one when they input it.  I'm not sure that works, but why else would they gather postage costs?

Yes, the book information comes from some outside databases. There are many reasons it can be wrong, and it often is.  It is generally recommended that people who want to print postage from the site, should probably invest in a scale to weigh packages before letting PBS print the postage.

If you want to correct it for PBS (which would be nice) you can submit a Book Data Edit with the correct information in it. When I am doing book edits for books, I generally put in the weight from Amazon for that ISBN ... although you will have to convert pounds to ounces, as PBS measures in pounds for some reason where Amazon measures in ounces.

Okay, I went and submitted a book edit for the weight.  

Thanks all!

Someone likely meant to put in 9.5oz and didn't realize they had to convert that to pounds for the data entry. Thanks for doing the data edit!

In case it is helpful, here's a handy online tool I use to convert ounces to pounds: http://www.calculateme.com/Weight/Ounces/ToPounds.htm

I got a small postal scale so I could weigh my own packages because yes, sometimes the weights on here are wrong.   You really have to make sure it's right before you print postage for the wrong amount.

Just today, I had a graphic example of how those little errors in the database can cause a problem... I had a PBS member request seven books off of my Bookshelf. If I had blindly used the PBS weight, I would've had to pay almost a dollar more than was actually necessary. I realize one buck isn't a lot in the overall scheme of things. However, to quote one of our Founding Fathers: "A penny saved is a penny earned"!

That's true, Ed.  If you paid a dollar more on most or all of your transactions on here, it would add up fast!  Unfortunately sometimes the totals are way below what the real amount ends up being.

If you use PBS printed postage and have a postage scale, it's easy to change the weight before printing the postage.