It used to be that paperbacks only came in one shape 6 3/4" tall by 4 1/4" wide and were as fat as necessary. Now they are all over the place. It's stupid of me but I don't like it when the books in my sets are in different sizes. Is there a way I can figure out if the book I am looking at is not the classic paperback shape, or if it comes in a variety of print formats?

If you click on the title, then click on "more options" --> "edit book data" you can see the measurements that have been entered for the book.  There's nothing official about them -- when a member posts a book it has to match the title, author, ISBN, book type, and, if mentioned, Large Print.  Dimensions are entered to help the software figure out the right postage, but a book doesn't have to match the dimensions.  They are often correct, though.

You can look the ISBN up on another site, such as Amazon, or do a google search for the ISBN with a word like "inches."  Sometimes you'll get a good idea of the size of the book.

A problem with both of these methods is that publishers sometimes issue two or more editions of a book with the same ISBN.  So even if a books dimensions are listed correctly, it's possible that there's another book out there with the same title, ISBN, etc., but a different size.  If it's the same book type (paperback, for instance) it would be postable to the listing.

A possible solution is to set up a requestor condition with the dimensions of the book you are looking for.  You'll get senders who decline because they don't want to take the time to measure their book or don't have a measuring tape handy, but it could work for you.  Or you could mention a visual clue such as "the cover has a round circle in the top left corner with the letters BT in it." Requestor conditions are set up in "Settings" which you'll find on the My Account menu.

Great answer Patty

If the data isn't available in the PBS book data info, the Amazon link is a fast and easy route to research book size.