How Many Books Have Ever Been Published?

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When Johannes Gutenberg invented the printing press in 1440, he couldn’t have foreseen how his humble creation would eventually lead to a global industry churning out millions of books each year. In the centuries since, new books continue getting published while old books pile up so that the total number of books that exist would be inconceivable to a man who placed every letter by hand. While counting up all the actual individual texts populating bookstores, public libraries, and private collections throughout the world would be a Sisyphean task, there might be a way to at least approximate how many unique book titles have ever been published.

Trying to determine how many books there are first raises a deceptively simple question: What is a book, anyway? That can get deeply philosophical very quickly, and there’s no single answer to it. The team behind Google Books (whose ambitious goal is to digitize all printed material, allowing unprecedented access to the world’s knowledge in a single database) came up with their own definition in 2010, in an attempt to answer this thorny query: What they refer to as a “tome” comprises an “idealized bound volume,” covering the range from a bestselling novel with copies available at every airport newsstand to a rare, leather-bound out-of-print edition to a single catalogued manuscript of someone’s PhD dissertation going quietly unread in a university collection.

On its surface, this definition replicates the concept underlying International Standard Book Numbers (ISBN), the universal identifiers for all books in the commercial marketplace. However, ISBNs have only existed since the mid-1960s and have yet to be widely adopted in non-Western regions of the world, so relying solely on that single number omits vast portions of printed material. Even when they are used, the process of assigning ISBNs isn’t particularly rigorous, so plenty of “book-like objects” that are definitely not books come with an ISBN: audiobooks, instructional DVDs, flash cards, etc. Relying solely on ISBNs to determine the number of published books offers a murky, unsatisfying answer.

Other institutions have attempted to standardize their comprehensive book catalogs, among them WorldCat and the Library of Congress, but these numbers are even more likely to be assigned in multiples to the same titles due to different cataloguing rules. Simple titles, author names, and publishing companies are less reliable still, as human error in transcribing all that information into a database can also lead to duplicates.

The success of Google Books’s attempt at solving this problem takes into account all these various shortcomings, and uses them to cross-reference nearly a billion raw records from 150 distinct providers to narrow down the number to just one of each book. After weeding out all the assumed duplicates, there are still certain non-book entries that need to be discarded, including two million videos, two million maps, and a turkey probe that was once added to a library card catalog as an April Fools' Day joke. All told, Google Books came up with—drumroll, please!—129,864,880 books total. Phew.

But wait, there’s more! Despite Google’s best efforts, their algorithm fails to account for certain crucial factors: Not only is their calculation outdated, having been tallied in 2010, but it predates the recent surge in self-publishing, especially in digital formats. Though ISBNs are recommended for all titles, they are not required for self-published works carried in most e-book marketplaces, and there is no reliable system for keeping track of them otherwise. As the popularity of self-publishing increases, with nearly half a million new titles released in 2013 alone, the Google Books algorithm only gets further from reality.

Until Google updates its methodology, we can at least do a little extrapolation with the data we have to figure out a more accurate number of published books in existence in 2016. It’s a moving target, relies on unreliable ISBNs, and will require some educated guessing along the way, but here it goes anyway.

According to Bowker, the organization responsible for keeping track of all newly assigned ISBNs in the United States, the years 2011 to 2013 saw the publication of nearly one million new titles (and maybe a few reprints). A U.S. Industry and Trade Outlook statistic indicates that the United States produces about 40 percent of the world’s printed material; if it would be fair to assume that the U.S. is responsible for a similar percentage of non-printed text, it becomes possible to estimate a figure for total global book production, which comes out to about 2,267,265 new books published worldwide from 2011 to 2013.

More recent data is hard to come by, so the best way of filling in the gap between 2013 and now may be to average book production over the last three years (755,755 new titles annually worldwide) and add that to the 2013 total. After some basic arithmetic, it seems that a low threshold for the number of unique books in existence as of halfway through 2016 is (another drumroll, please) 134,021,533 total. And that’s all she wrote—for now, anyway.

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