IngramSpark Study: Better Book Metadata Increases Sales by Up to 22 Percent

By The Publishing Times Editorial Team

A new study from IngramSpark — one of the largest print-on-demand and book distribution platforms for independent publishers — has produced the clearest quantitative evidence yet that book metadata optimization directly drives sales. The study analyzed 2,000 print books and found that titles with improved metadata outperformed their unimproved counterparts by an average of 9 percent in the United States and 22 percent in the United Kingdom.

For self-published authors who have treated metadata as an afterthought — filling in the minimum required fields to get a book listed and moving on — the IngramSpark findings represent a significant and actionable opportunity.

What the Study Actually Measured

IngramSpark divided its sample of 2,000 print books into two groups: those with basic metadata (the minimum required for distribution) and those with optimized metadata meeting a specific set of criteria. The optimized group was required to have three specific BISAC subject codes, Thema subjects and qualifiers, at least ten keywords, and regional subject classifications.

The results were consistent across both markets studied. In the United States, improved titles outperformed unimproved titles in 41 out of 52 weeks and in 11 out of 12 months over the study period. In the United Kingdom, the average sales lift was 22 percent. Perhaps most notably, older titles that received metadata improvements declined 8 percent less year-over-year compared to the unimproved group — suggesting that metadata optimization has a meaningful impact on backlist performance, not just new releases.

Why Metadata Matters More Than Most Authors Realize

Book metadata is the structured information that tells retailers, libraries, and discovery algorithms what a book is about, who it is for, and where it belongs in the broader catalog. When a reader searches for "cozy mystery set in Scotland" on a retail platform, the results they see are determined almost entirely by metadata — not by the book's content, reviews, or author reputation.

The problem is that most self-published authors approach metadata the way they approach tax forms: fill in what is required, get it done, and never look at it again. IngramSpark's study demonstrates that this approach leaves measurable sales on the table.

The specific metadata elements that drove the study's results are worth examining in detail. BISAC subject codes are the industry-standard classification system used by retailers and libraries to categorize books. Most authors assign one or two BISAC codes; the IngramSpark study found that three specific, accurate codes significantly improved discoverability. Thema subjects and qualifiers are a newer international classification system increasingly used by global retailers — particularly relevant for the 22 percent UK sales lift, where Thema adoption is higher than in the US. Keywords — at least ten, according to the study's criteria — are the search terms that connect a book to reader queries on retail platforms.

How to Audit and Improve Your Book Metadata

The practical implication of the IngramSpark study is straightforward: every self-published author with books distributed through IngramSpark should audit their metadata at least once a year, and ideally once per quarter for active titles.

The audit process starts with BISAC codes. Log into your IngramSpark account, pull up each title, and verify that you have assigned three accurate BISAC codes — not just the broadest possible category, but specific subcategories that reflect your book's actual content and audience. A thriller set in a hospital should have codes for both Medical Thrillers and Psychological Thrillers, not just the generic Fiction / Thrillers category.

Keywords deserve particular attention. Ten keywords is the minimum threshold identified in the IngramSpark study, but the quality of those keywords matters as much as the quantity. Effective keywords are phrases that readers actually type into search bars — not the author's name, not the book title (which is already indexed separately), but the specific descriptive phrases that match reader search behavior. "Cozy mystery female detective small town" is a useful keyword phrase. "Entertaining mystery novel" is not.

Thema codes are the least familiar element for most US-based authors, but their importance is growing as global distribution expands. IngramSpark's metadata interface includes Thema code selection; taking the time to assign accurate Thema subjects and qualifiers is a low-effort change with measurable impact, particularly for authors with meaningful UK or European sales.

The Caveat Worth Stating

IngramSpark's own analysis includes an important qualifier: good metadata will not save a bad book. The study's results apply to books that readers want — metadata optimization makes those books easier to find. A book with poor reviews, an unappealing cover, or a weak product description will not be rescued by optimized BISAC codes.

The right mental model is that metadata is the infrastructure of discoverability. It does not create demand; it routes existing demand toward your book rather than a competitor's. For authors who have done the hard work of writing a good book and presenting it well, the IngramSpark study suggests that a metadata audit is one of the highest-return, lowest-effort improvements available.

Frequently Asked Questions

What did the IngramSpark metadata study find?
IngramSpark analyzed 2,000 print books and found that titles with optimized metadata — including three specific BISAC subject codes, Thema subjects and qualifiers, at least ten keywords, and regional subjects — outperformed unimproved titles by an average of 9% in the US and 22% in the UK.

What is a BISAC code and how many should my book have?
BISAC (Book Industry Standards and Communications) codes are the standard classification system used by retailers and libraries to categorize books. The IngramSpark study found that three specific, accurate BISAC codes significantly improved discoverability compared to one or two generic codes.

What are Thema subjects and why do they matter?
Thema is an international book classification system increasingly used by global retailers, particularly in the UK and Europe. Assigning accurate Thema subjects and qualifiers to your IngramSpark titles improves discoverability in international markets.

How often should I audit my book metadata?
IngramSpark recommends auditing book metadata at least once a year. For active titles or books in competitive categories, a quarterly review is advisable to ensure keywords and subject codes remain accurate and competitive.

Does better metadata help backlist titles?
Yes. The IngramSpark study found that older titles with improved metadata declined 8% less year-over-year compared to the unimproved group, suggesting metadata optimization has a meaningful impact on backlist performance.