I realize there's going to be a bit of variation here from one author to the next and depending on length of the novel, but the range shouldn't really be too large.

The thing is, I really have no idea where the middle of that range lies. 5,000 words? 10,000? 20,000? I know the average adult vocabulary (in English) ranges between 20,000 and 30,000 words, although I don't know if that number includes variations (like, likes, liked, liking), but I would expect this number to be significantly less than the full breadth of a person's vocabulary.

I had trouble finding any information. Is there anyone who is familiar with this subject?

  • Retag at will, Captain(s). Commented Jan 5, 2013 at 23:35
  • Zipf's Law governs the expected count of unique among a text of n words total.
    – Vorac
    Commented Aug 11, 2020 at 12:02

7 Answers 7


I pieced the below data together from a number different websites. Basically putting the text versions of the three titles shown, individually into a site that can quickly filter out the unique words. I then used the data to feed into a homemade random word generator to be used it typing practice.

It is more challenging to get newer titles, but this gives a cross section of what you could come across.

Hope this helps.

  • A Separate Peace, by John Knowles

    • Word Count: 54,050
    • Unique Words: 6,418
  • The Outsiders, by S.E Hinton

    • Word Count: 49,444
    • Unique words: 3,898
  • Catcher in the Rye, by J.D Salinger

    • Word Count: 74,193
    • Unique words: 4,206
  • Hi Author104, welcome to writing.se! Take the tour and visit the help center for more information. This is a great first answer! Well done on gathering such good information. I find the differences in % of unique words fascinating. Thanks for participating and happy writing!
    – linksassin
    Commented Oct 14, 2019 at 7:00

You know that you have an important question when your topic already has a recognised acronym NDW.

However it is typically used in the medical field rather creative writing. It appears to have arisen from the rehabilitation of patients with brain injury such as stroke.

The University of Albert Department of Linguistics has a fairly extensive discussion on using NDW as one measure (among many) in interpreting the complexity of texts.

And the short answer to your good question: IT DEPENDS on a huge range of factors. Any "average" value is likely to be meaningful only for the sample from which it was calculated. You could calculate an NDW for Stephen King novels but that would have little value in making predictions about the work of Umberto Eco.

A concordance of the Bible gives an interesting way to examine some of the issues. (Although this is KJV. I would be interersted to see the differences in GNT.)

  • That's the University of Alberta (Edmonton, Canada).
    – user23046
    Commented May 11, 2017 at 18:33

Okay so I was a bit curious about this. Wrote a little script for myself and ran it with some random books. I used epubs of books I bought and converted them to .txt via Calibre to access the text more easily in Python. I basically split them on spaces and stripped away special characters, keeping newlines in mind.

The Way of Kings - Brandon Sanderson: 15206 unique words (383k words)

A Court of Thorns and Roses - Sarah J. Maas: 8293 unique words (130k words)

Vampire Academy 1 - Richelle Mead: 6357 unique words (79k words)

Shadow and Bone - Leigh Bardugo: 6628 unique words (81k words)

A Game of Thrones (ASOIAF 1) - George R.R. Martin: 11946 unique words (292k words)

Just throwing some random ones in there really to give people some more examples.

Note that there might be slight variation in these numbers, but I checked it on some of my own stuff and word-wise it seems to at least approach e.g. Word's own total word counter (vs what my counter spits out). Of course, I'm sure there are niche words I might have missed or accidently split like hyphenated words, contractions, and conjugations of the same word, so just keep that in mind. It at least comes very close to the real number(s). Total word counts shown here were obtained via quick Google search so they might vary slightly too.


While I can't answer the "big" question of an average, I can answer the smaller question of whether anyone's heard/seen anything on the subject before. If anyone has answered a question like this I would assume it would be Franco Moretti or someone doing similar computational research into the statistical profiles of large literary corpora.

Wired did an article on Moretti's research a few years ago. He floats a concept of "distant reading" wherein we cover a lot of ground traditional criticism can't meaningfully cover through statistical methods. I haven't read him widely, so it's possible he's covered this somewhere. I've emailed him before and he was responsive to my questions, though I note from his faculty page that he's on leave this year which may have some effect (as might any pending publications he has on the topic). He also has related books, like Graphs, Maps, Trees & Distant Reading.


I originally posted this in another form as a comment, but I think it deserves an answer. However, I will not answer it as-asked, but as-interesting.

At least in the USA educational system, there are criteria for selecting appropriate reading materials. I refer not to intellectual, moral, or social content, but to readability.

The concept is that at any point in time, each student has a certain reading level, which can be measured. Then, the student should be assigned reading materials at a slightly higher reading level, so that the level gradually increases as more and more difficult material is assigned.

There are several quantitative methods. One of them, private copyrighted and trademarked, is known as "Lexile." There are others. The inputs to the calculation vary with the method. I believe that Lexile is proprietary, so its exact algorithm is not publicly known. Other methods are publicly known.

One possible input to the calculation, among others, is the number of different words used in the book. That may be scaled for whether the words are unusual in usage or unusually long.

However, this can be gamed. Many famous novels are simply written, despite their profound content. That was intentional. They were written in an era when education was taken seriously at each grade level, but most folks did not graduate high school. Thus, they are written so that someone at about the eighth grade level of reading (real grade 8, not "everyone passes") can read the book. But then, such books would not be sufficiently "advanced" for typical native-English readers in grade nine! Here's an example: Grapes of Wrath, by John Steinbeck.

Thus, some authors will intentionally include more words, unusual words, and longer words, in order to raise the reading level. That helps their otherwise-obscure book score better for more advanced readers, even if the intellectual content is much lower. Especially in fantastic fiction, there may be many characters with unique names (no wizard is ever named "John"), places, and even objects.

  • For me it is frightening to think that books are chosen like this. Surely everyone who loves reading read things they didn't understand and reads things that are too easy for them. Commented Jan 2, 2019 at 22:26

Last year, I looked up average word counts for Historical Fiction (which is what I write), but I ended up taking notes for several other genres (though not all) out of curiosity. Here they are:

  • adult novels in general: 80,000-100,000
    (this includes literary, crime, romance, ...)

  • sci-fi and fantasy: 90,000-115,000
    (though the limit 120,000 is often mentioned too)

  • historical: 90,000-110,000
    (though the limit 120,000 is often mentioned too)

  • mystery: 70,000-90,000
    (though Agatha Christie's average was 40,000-60,000)

  • romance: 50,000-100,000
    (so, from really short to general adult novel length)

  • YA: 55,000-80,000
    (though 55,000-70,000 is often mentioned too)

At the time, I saw tens of pages until I came up with these averages, since some websites had conflicting numbers for some genres, but here are some of the first links to pop up after a similar google search:

link 1
link 2
link 3
link 4

  • The questioner was asking for number of different words, but still fun trivia facts.
    – Jason Bray
    Commented May 12, 2017 at 19:36

This is almost impossible to answer with any degree of accuracy as it depends on so many variables. However, as a very rough and general guide the average novel length is about 80-100,000 words of which about 5-10,000 words would be unique and differentiated.

  • I'm curious: did you get this data from somewhere?
    – J.R.
    Commented Jan 8, 2013 at 9:08
  • J.R. Yes! But as I said, there's so many variables involved this is just a very rough estimate. Commented Jan 9, 2013 at 13:28
  • 4
    @spiceyokooko - I believe that J.R.'s comment may be asking you to cite those numbers. (I'd also be curious to know where you got them, and what years those numbers represent, since the average novel seems to have gotten longer in the last decade or so.) Commented Jan 10, 2013 at 5:17
  • New answer just brought me back to this question almost 2 years later. Still not happy with any of the answers, even though I'm itching to accept. Haven't been around much for awhile-- glad to see the beta's still going :) Commented Nov 24, 2014 at 21:26

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