(I'm not sure this question fits here but this site seems the most appropriate within stackexchange network...)

I'm trying to buy a some book from NHBS (a field guide). The problem is that the same field guide is often printed in 2 versions:

  1. smaller one for usage in the field,
  2. bigger one for comfortable reading at home.

The question is: will both versions of the book have different ISBN, or it might happen that they have the same ISBN? Note that the dimension is often the only difference between the two versions, the publisher, year etc. will be the same. Does ISBN uniquely identify a book dimension?

(Background: I must order the book from NHBS (my company rules), but NHBS doesn't publish dimensions of the book. So I look up the book dimensions on Amazon and then look at the ISBN, if it's the same. But then I must know that ISBN will surely differ for both formats!)

5 Answers 5


It absolutely SHOULD be different for both formats. That said...

If it were published by a big publisher, I'd be totally confident that it would be. But I don't know anything about the NHBS, so it's not impossible that they've gotten a little sloppy and not bothered. And Amazon is a bit worrisome because they have their own book numbering system, and tend to include the ISBN as a detail, rather than their primary identifier. So they might be a bit sloppy as well.

I looked at the books, and given the price involved, I think I'd give the company a call and make sure you're getting the right thing. Personal contact can be fun.

  • 1
    thanks Kate! I checked few guides and it seems that ISBN always differs among formats... I hope it's an "iron" rule. Though I like personal contact in other situations :), giving a call to internet shops can be sometimes tricky; I prefer to know from the order form itself that I buy the right thing :-) Thank you,
    – Tomas
    Feb 3, 2012 at 13:07
  • 4
    They're supposed to. But according to the rules, for example, all different e-book formats are supposed to have different ISBNs, and that's VERY rarely the case. So, again, if it's a big company putting out the book, I'd trust that they're following the rules. If it's a smaller company, it's less of a guarantee.
    – Kate S.
    Feb 3, 2012 at 14:46
  • Kate, yes, these are publishers like Collins, Princeton etc.... Thanks
    – Tomas
    Feb 3, 2012 at 16:01

I'm working with a writer who's self-publishing, and she had to get a different ISBN for the hardcover, softcover, and eBook versions of her novel. I remember reading somewhere that if you issue a new version of the book (change the content in any significant way), you need a new ISBN as well. So yes, it should be different, but I agree with Kate's suggestion to call the company and find out.


I am pretty sure that the ISBN number would be different if the dimensions of the book were not the same. I know that ISBN numbers are not the same when the paper stock is changed to be "acid free", so even with the same dimension a book could have different ISBN numbers.

Publishers use ISBN numbers to keep track of their inventory and costs/profits, etc... So they certainly would want to know which dimension of the book was ordered more often, and of course the buyers would want think that if they ordered a book with the same ISBN number as someone else they would get the same identical book.

However I would think it is up to the publisher to decide. For instance, if there was a minor adjustment to the paper size and they were no longer going to be offering the older size, the publisher may just decide to keep the same ISBN number.

To summarize:

  1. Different versions of the book may have different ISBN, or may have the same ISBN

  2. ISBN does not uniquely identify a book dimension.


Officially, you should have a new ISBN number for every version of your book, including dimension sizes. the only exception is for minor grammatical, spelling, punctuation and minor editing purposes. If there is a change in a character's name or more than 5 paragraphs in the whole story are altered, it is considered a new Edition and needs a new number.


Although I keep hearing that the answer should be "yes", the answer is definitely "no".

As an example, I am currently holding two copies of the book "Cauldron" by Jack McDevitt. Both have the ISBN of 978-0-441-01525-2. However, one of them is the "full sized" hardcover (~ 9.25"x6.5") while the other is a smaller edition, often associated with book clubs (~ 8.5"x6"). I've seen this before as well. I wish I knew why this is the case but, sadly, I only know that it is the case.

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