When ordering books how can you tell which one are mass market paperback size?  Sometimes they say mass market, but sometimes there will be two paperbacks listed, with difference ISBNs and I can't tell a difference.

Well, I go to amazon or other sites to check on this, as usually the information is not in the PBS database.

If it is in the PBS database, you can look at the "book data Edit" page to see what the measurements are.

That is not foolproof, though, because if the same ISBN has been used for the trade and the MMP size, then only one size can be listed in the PBS database ... and you would not be able to tell that there is also a different size. And many books have no measurements, anyway.

I do the same thing.  It can be a guessing game.  I prefer mmpb's myself, but more and more the publisher's are going to the larger size pb's.  In a way it's nice because the print is a little larger usually.  But as I get older the larger sizes are more cumbersome to handle.  I think Amazon is usually you're best bet.

Ruth

I use Amazon also because I don't like reading MMP. So anything that is less than 5 inches wide I won't order.