how come some of the heavier books don't count as two credits? I recently mailed out two books that cost me 5.09 (media mail) to ship each. This is

a bit more than double the average shipping cost of a book.

Of course I mailed them promtly and without a word to the requestor...but does anyone else have this happen often enough to wonder if some books should be an additional credit?  Especially being that PBS estimates out a weight and shipping cost for you?

Books will rarely exceed 2-3 pounds, let alone 7 pound books you apparently mailed, so it really isn't normally that much difference and the site isn't going to sacrifice the simplicity of the 1 book = 1 credit for the small variances that are the norm. If a member wants to even it out, they can order heavy books with the credit the earn to mail one.

The other problem is that the weights in the PBS system are from outside sources. Many books don't have any weight on them at all or are an outrageous number (I've found two entered at 20 pounds). The system is off a good amount of the time and there is no way they can build a credit earning system based on numbers that could be wrong a third of the time.  It really isn't feasible to base the credits on weight.

What books did you mail that cost that much?  I've mailed really thick hardcover large cookbooks that only cost about $3 to mail.  There's a warning on the label printing page to varify that the weight is correct. PBS gets its info from several sources and it isn't always correct. 

There are other trading sites where you can ask more but PBS is a 1 credit = 1 book.  If you request similar books to what you send then it averages out. 

The weights were correct...took them to the post office for postage & mailing.  One was a hardcopy of Drood and the other was a hard copy of Les Miserable.

its fine..didn't mean to stir up the pot here with weights & costs.

How much packaging are you using? Amazon shows Drood as weiging 2.4 lbs and Les Mis about 2lbs for hardcovers.  Which wouldn't be $5 to mail.  Did you add DC through the post office?  If so than you paid too much for DC-it's cheaper through PBS and PBS doesn't honor outside DC.  I would also check my receipt and see if they charged me for media mail.  They don't use mm unless you ask them for it or they see it in on the package.

I sent five books media mail last week (3 of the hardbacks) and it cost me less than $5.00.  You would have had to send out over 7 pounds of books to get to five dollars.  

I second the motion for a scale - I looked at a paperback book on a shelf today and it said it had 3,073 pages. The weight that will show is going to be off...by quite a bit.

I've mailed a lot of hardbacks, but I think the most I've paid was $3.16.

She said it cost over $5 each book which just doesn't make sense unless she used a really large box.  I can't see either of those books weighing 7lbs.  Yes they're both long books but even in hardcover Amazon has them at less than 3lbs each. 

Wow, I sent a 4 lb textbook out to someone here on PBS just last year for about $3.50.

I find it's better to tell the postal workers how you want it sent, "media mail," first class," etc. Sometimes when I just said "the cheapest way" I swear they didn't bother actually selecting the cheapest way (this was when I sold on Ebay a few things here and there). I think they had me sending things Priority when I could have sent them First Class. I didn't really understand the different ways to send things until coming here.

...but does anyone else have this happen often enough to wonder if some books should be an additional credit? 

The only times that I have sent anything over 7lbs on PBS involved deals of ~50 books each.

But you can control how often this happens by deciding not to post heavier books. It might be more cost effective to trade them locally.

My guess would be that they were sent Priority Mail and not Media Mail.  Next time tell the PO that they are books and you want them to go Media Mail.  You need to use your own packaging and not the free Priority Mail packaging.

ETA:  Check your postal receipt.  Even if you asked for Media Mail the counter clerk may have not chosen that class of mail.