I always hate paying the minimum 2.60 to ship very tiny books. I did some digging. Any book that is under 13 ounces and LESS THAN 3/4 inch thick in an envelope can be sent as a large envelope/flats through usps 1st class....each ounce is a different price with 1 oz being .94 with the max savings at 8 oz at 2.41. So, if you have a book that fits this criteria, you can take it to the po or just look up the price list for flats and put postage on yourself! So happy i found this!! Wish I had found it sooner! 

envelopes can't have tracking on them can they?

No you would just be sending with postage 

Make sure that the envelope and book inside is thin enough to qualify as a first class flat, envelope.  Otherwise, the p.o. has been known to charge the receipient postage due. As someone that has received 2 books postage due from buying on sites like Ebay and Amazon, I can tell you that it happens and it's not a good thing.

On a side note, I've noticed that the PBS page to get the wrapper hasn't been updated (possibly for years) and often doesn't give the correct estimate for weight or postage pricing for first class package weights.

Max thickness is 3/4 inches which most kids books are less than that. 

Yes, I have a few of those myself. Those would be okay.   I was thinking of the sort of on the thin side mass market paperbacks that I had to pay postage due charges on.

Yes, I think you are talking about First Class Parcel.  It also can have tracking. I use Paypal Shipping and it is an option for under 8 oz which can include MMP and is always less than Media Mail rates.  If you weigh your book before sending there shouldn't be postage due.

I found this link that is very good describing the postage rates and when it is better to send First Class.

http://www.paperbackswap.com/help/help_item.php?id=515

I also just found info on large envelope flat first class.  It also has to be larger than 6 1/8 x 11 1/4.  I think most children's books aren't that large even if they're less than 3/4 inch thick.

To decide if First-Class Large Envelope (= First Class Flat) Rate will work for your book:

• Check the dimensions (length/heighth):

• • Cut a sheet of printer paper to 6- 1/8 inches by 11-1/4 inches. 
  • Place your book on it so that the long side of your book is parallel to the long side of the paper, centering the book on the paper
  • If your book overhangs the paper edge on either the long or the short side, you have passed the length/heighth criteria, and you should then check the thickness of the book
  • If your book does NOT overhang the paper, it does not meet the heighth/length criteria, and needs to be sent package rate (First Class Parcel or Media mail).
• Check the thickness:
  • If it is greater than 1/4 inch but less than 3/4 of an inch, then it meets the thickness criteria, and you should then check the weight
  • it it is thinner than 1/4 inch or thicker than 3/4 of an inch it does not meet the thickness criteria, and needs to be sent package rate (First Class Parcel or Media Mail).
• Check the weight
  • If it weighs more than 3.5 ounces but less than 13 ounces, it meets the weight criteria, and you should then check flexibility.
  • If it weighs less than 3.5 ounces or more than 13 ounces, it does not meet the weight criteria, and needs to be sent package rate (First Class Parcel or Media Mail).
• Check the flexibility
  • If it is able to flex greater than 1 inch in all directions (the spine/binding usually prevents this in a softcover book--try to flex the two short sides to meet each other, in other words), it meets the flexibility criteria, and you can send this book using First Class Large Envelope (aka First Class Flat) rate.
  • If not, it does not meet the flexibility criteria, and needs to be sent package rate (First Class Parcel or Media Mail).

You cannot simply put your small book into a large envelope to try to qualify for Large Envelope rate--this will not work, since the package will not be uniformly thick.

• Also you run the risk of the loose envelope flap getting caught in postal sorting machinery and damage to or loss of the book inside.  We recommend that all packaging be taped down tightly around the book to prevent this.

In summary: The great majority of books cannot be sent using First Class  Large Envelope/Flat rates.  First-class PARCEL rate is usually the appropriate first-class rate for a book. 

Yes do keep in mind that they have to be flexible as well, hardcover books like Golden Books wouldn't work. A book that is too small is OK, it can go in a larger envelope, just make sure to use packing tape all around the envelope. 

Becca,  The directions I listed above specifically say it can't be too small.  Does PBS have that wrong?

Edited to correct spelling.

It is the size of the envelope that is important. 

This info is not completely accurate. The flat needs only to exceed one of the minimums of length height or thickness and cannot exceed the maximums in any direction of l 15, h 12 & thickness 3/4

Is PBS going to update since the price drop? Up to 3 ounces parcel rate is only 2.45. And what is the difference between media mail and library Mail? 

It does NOT have to be sent package rate if under 1/4 inch

And yes you can put a smaller book in a large envelope as long as there is less than 1/4 inch variance. The uniform rule allows for 1/4 inch variance. 

And you exclude the outer edge (1 inch) with the uniform rule (I'm getting all this from the usps site)

All letter-size pieces over 3.5 ounces are prepared as letters and charged the flat-size prices (so if it's under 3.5 ounces the minimums don't matter anyway) 

Library Mail is only for libraries to use, it's the same as media mail just slightly cheaper. It's not applicable to PBS users. 

First class flats are not library mail. 

Most books will NOT qualify as a flat.  It has to be flexible on both the long side AND the short side.  The spine of the book does not normally flex enough for the item to be considered to be a flat instead of a parcel.

I've rarely used the First Class Flat rate, and not for books. And yes, in my experience the package can be too small for the rate.

You can however (as mentioned in Theresa's first post) send books regular First Class...I haven't done this in awhile, but below the 8 oz mark it is actually cheaper to use First Class and doesn't have the restrictions of the parcel rate.