Turns out it’s quite a lot and of course, it was Google that attempted to figure out the precise number:
Ever wonder just how many different books there are in the world? After some intensive analysis, we’ve come up with a number. Standing on the shoulders of giants—libraries and cataloging organizations—and based on our computational resources and experience of organizing millions of books through our Books Library Project and Books Partner Program since 2004, we’ve determined that number.
As of today, we estimate that there are 129,864,880 different books in the world. That’s a lot of knowledge captured in the written word! This calculation used an algorithm that combines books information from multiple sources including libraries, WorldCat, national union catalogs and commercial providers. And the actual number of books is always increasing.
Ultimately, it is truly incredible to fathom the depth and breadth of published works out there in the world. To find out how we calculated this number (no, we didn’t count them on our fingers:), check out the Google Books blog.
At some point the world is going to need online librarians, experts who can curate the vast streams of digital knowledge.