Two meanings of the same word
In traditional publishing, a blurb originally meant a short endorsement — the praise quote another author contributes to a jacket. In self-publishing the word almost always means the selling description itself: the copy on the back cover of a print book and in the description field of a retail page. Both meanings coexist, so when a designer or retailer asks for the blurb, confirm which one they need.
What belongs in the blurb
Give the reader a clear point of view, a concrete desire, the force blocking it, and stakes that make the outcome matter. Cut subplots, cast lists, and vague praise. Fiction blurbs run on tension and voice; practical nonfiction should make the reader, problem, method, and outcome explicit. End on the open question, never on the answer — a blurb that resolves its own hook removes the reason to buy the book.
How long it should actually be
Word counts are guidance, not law. Around 100 to 200 words fits most back panels comfortably, but the honest test is the physical context: place the copy on the real back cover at final type size and check line length, paragraph breaks, barcode clearance, and where a phone retail page truncates the description. Shorter copy with clear paragraph breaks usually outperforms a dense wall of text.
Where the blurb lives on a print book
On a paperback, the blurb anchors the back panel of the full wrap, sharing the space with an optional author bio, review quotes, and the barcode zone. The background behind it should calm down even when the front cover is busy — a readable blurb column is part of cover design, not an afterthought. Coverfairy keeps back-cover copy as an editable text layer of the same wrap, so revisions never require rebuilding the file.
Sources: Reedsy guide to writing a book blurb. Reviewed ; recheck the official page before production.