The industry’s self-publishing segment continues to thrive, according to data recently released by Bowker. The number of new self-published titles that have both ISBNs and BISAC codes was 2,298,004 in 2021, a decline from the two previous years, but still well above the 1,551,391 titles registered with Bowker in 2018. In 2021, there were 2,300,336 new self-published titles with only ISBNs, a 15% decline from 2020.

The number of self-published ISBNs issued topped one million for the first time in 2017 and had a huge spike in 2019, which Bowker attributed to a large order from a major self-publishing platform. Figures include ISBNs for print books, e-books, and audiobooks.

Fiction was the most popular self-publishing category, with 335,428 ISBNs registered. Juvenile nonfiction and fiction were in second and third place, respectively, with business/economics and literary collections rounding out the top five.

Bowker marketing manager Andy Kovacs pointed to several factors behind the ongoing interest in self-publishing. Topping his list is the increasing number of inexpensive and high-quality publishing and distribution services that make it easy to produce a book in a variety of formats. Closely tied to that development is the increasing appeal to authors of the hybrid publishing model, which gives them the ability to publish with traditional publishers and use nontraditional platforms. A survey conducted last year by Bowker of authors who acquired ISBNs found that 11% are published by traditional houses but were also doing some self-publishing. Twenty-two percent of writers who took part in Bowker’s survey considered themselves to be professional authors.

The surge in popularity of audiobooks has inspired authors to use the medium to showcase their work, Kovacs said, adding that the need for fresh content to meet the needs of the film, television, and online streaming industries has also encouraged authors to write books they feel are potentially adaptable to stage or screen.

Kovacs expects that the demand for self-publishing will continue to hold steady as new technologies emerge and the public continues to seek quality content.

The actual dollar size of the self-published market has always been murky at best. A new report by Bookstats sheds some light on the matter. According to Bookstats, which collects online sales data in real time from Amazon, Apple, and Barnes & Noble across the print book, e-book, and digital audiobook formats, self-published authors captured 51% of overall e-book unit sales last year and more than 34% of e-book retail revenue, compared to 31% in 2021. Those numbers translate into e-book sales of $874 million in 2022 for self-published authors.