Readers who love long books might want to check out the classics. I’m catching up on the classics as I write this post, which may take some time. Currently, I’m reading An American Tragedy by Theodore Dreiser. Unfortunately, I could only get my hands on a mass-market, paperback size, which makes reading a book of that heft less pleasurable than it should be. The audiobook runs 34 hours and 12 minutes, so I think I’ll stick with the paperback version. Still, that’s a shorter time than listening to Mark Twain: The Complete Novels, weighing in at over 58 hours–well over the standard American workweek.

Here is a nonexclusive list of long books I’ve read:

Gone with the Wind by Margaret Mitchell

And Ladies of the Club by Helen Hooven Santmyer

The Wheel of Fortune by Susan Howatch

The Royals by Kitty Kelley

The Love Songs of W.E.B. Du Bois by Honoree Fanonne Jeffers

Empire of Pain: The Secret History of the Sackler Dynasty by Patrick Radden Keefe

The Triumph of Nancy Reagan by Karen Tumulty

Though I enjoy long books as a reader, I can’t necessarily pursue them in my role as a literary agent. I do agree with the saying “Never say never”; but so far, I haven’t been able to justify representing a book of over 1,000 pages.

As for the markets I serve as a literary agent, here is a basic guideline for what length is most likely to work:

Category stories, such as romance or mystery geared to a specific line: Approximately 55,000 words. Before starting your book, I recommend referring to the publisher’s website since each line’s requirements are distinct.

Trade-book novels: 80,000-100,000 words.

Nonfiction: 40,000-90,000 words. However, this guideline doesn’t include many academic works, such as Bible commentaries geared mainly to the academic market. And some tomes, such as biographies about past presidents and other figures, can be lengthy. However, major biographies tend to be written by historians with an eye to the general market.

Whatever book you plan to write, be sure the word count makes sense for the book, the audience, and the market. The more knowledgeable you as a writer are about your audience and market, the better author you will be; and the more likely you will be to find a great agent and publisher for your work.