How long should a book description be? KDP's 4,000-character limit, the tags that count, and the back cover

The limits: KDP's 4,000 characters and the 150 words it suggests

Amazon KDP caps a book description at 4,000 characters, counts every HTML tag towards it, and advises a description of about 150 words. Both figures are on the same KDP help page, Write a Book Description, read on 4 November 2026: "Note that we have a limit of 4000 characters for the description", and, in its writing tips, "Aim for a 150-word paragraph with sentences that are easy to scan."

The two numbers do different jobs. The 4,000 characters is a hard limit enforced by the form; the 150 words is advice. Plain English text reaches 4,000 characters at roughly 650 to 700 words, so a description written to KDP's own advice uses about a quarter of the space.

Other stores set their own limits. Apple Books, Google Play Books, Kobo and Barnes & Noble Press do not state a description limit on the help pages we could read, and the figures repeated in third-party guides for them could not be checked, so they are left out here. The safe course is a description that fits the tightest limit you publish to, then a check in each store's own form.

Why the tags count, and what they cost

KDP's counter counts what is in the box, not what the reader sees, so every bold, italic and paragraph tag uses characters. The help page gives the example itself: the word test counts 4 characters, but bolded as <b>test</b> it counts 11, because the 7 characters of tags are counted too. The count is the same whether you write in the text view or switch to the source code view.

The tags KDP accepts are <br>, <p>, <b>, <em>, <i>, <u>, <h4> to <h6>, and <ol> or <ul> with each item in <li>. The page says plainly that <h1>, <h2> and <h3> are not supported, that double spaces between words will not show on the detail page, and that empty brackets such as <> or <><> should be removed "to fix invisible character issues".

A description counted, tag by tag

The description below is for an invented novel, written for this guide in the shape most fiction listings use: a bold hook, two short paragraphs of story, a positioning line and two bullets. Counted in its source form, it is 136 words.

<p><b>A lighthouse keeper’s daughter. A ship that shouldn’t exist. One night to tell the truth.</b></p><p>Nell Tarrant has kept the Skerry Point light burning since her father’s stroke, and kept the island’s secrets for longer. When a schooner that sank in 1911 appears off the rocks in a winter gale, the village wants answers, and so does the young surveyor sent from the mainland to close the lighthouse for good.</p><p>As the storm cuts the island off, Nell must decide what she owes the dead, the living and herself, because the ship has come back for someone, and she is running out of reasons to believe it isn’t her.</p><p><i>The Keeper’s Light</i> is a haunting standalone novel of family, grief and the sea, for readers of slow-burn gothic mysteries.</p><ul><li>Standalone, no cliffhanger</li><li>Book club questions included</li></ul>

(The description is one line of HTML; the page wraps it to fit.)

The ratio is the useful part. With its tags, this description used 6.2 characters a word; without them 5.7. At those rates, 4,000 characters is about 640 words formatted or 700 plain. A nonfiction description with a heading and a long bulleted list spends more on tags, so expect its ceiling to sit lower.

How long the description should be, in words

Write the description to the reader, not to the limit: KDP's own advice is about 150 words, and the widely repeated ranges of 100 to 300 words are advice of the same kind, not a rule. No retailer page we read sets a minimum word count, and none sets a maximum in words; the only hard limits are characters (KDP) and bytes (IngramSpark).

The KDP page explains its reasoning. A description is "often a reader's first experience with the content of your book", read by someone "only taking a second or two to decide", so it asks for a first sentence that "draws them in", the main plot, theme or idea "only", the genre made clear, and language that is "short and simple".

How long yours should be depends on the book more than on any rule. A fiction description sells the premise and the stakes; a nonfiction one also has to say what the reader will be able to do, and a short list of what the book covers is the clearest way, which is why nonfiction descriptions tend to run longer and use more tags.

What KDP will not accept in a description

Review quotes, links, prices, dates, emojis and keyword lists are all refused in a KDP description. The page's list of what it "cannot accept" is more specific than most guides repeat:

• reviews, quotes or testimonials, and requests for customer reviews;
• phone numbers, postal addresses, email addresses or website URLs;
• advertisements, watermarks on images or videos, and promotional material;
• time-sensitive information, such as dates of tours, seminars or lectures;
• availability, price, or other ways to order;
• spoilers;
• Unicode emojis;
• keywords or book tag phrases;
• pornographic, obscene or offensive content.

Two of these trip authors up most often. A line of praise from another author is a quote, so it cannot sit in the description; and a row of search phrases at the bottom ("cozy mystery, small town, amateur sleuth") is the keyword padding the last rule forbids.

IngramSpark counts bytes, not characters

IngramSpark limits the full description to 4,000 bytes and the short description to 250 bytes, so curly quotes, dashes and accented letters use more of the allowance than plain letters. Its Global Discoverability Guidance (IngramSpark staff, 1 May 2024, updated 10 February 2025) says "each book description field has a byte limit" and suggests an online byte calculator. In UTF-8, the usual way text is stored, a plain English letter or space is 1 byte, an accented letter such as é is 2, and a curly apostrophe, a curly quote or a dash is 3.

That makes the same text count differently at the two stores. The sample above is 845 characters for KDP and 857 bytes for IngramSpark, because its six curly apostrophes cost 3 bytes each. A description written up to KDP's limit, 3,990 characters with 40 curly quotes and apostrophes and 5 dashes, comes to 4,080 bytes: 80 over at IngramSpark.

IngramSpark also allows fewer tags. Its list is <p>, <br />, <ul>, <ol>, <li>, <em> or <i>, and <strong> or <b>, with no active hyperlinks. KDP's list has no <strong> and IngramSpark's has no <u> or headings, so for one description that works in both, stick to the tags they share:

The 250-byte short description is a different job: about 40 words, one or two sentences that stand on their own. Count it in bytes too; the character counter shows UTF-8 bytes beside the characters you see.

How long a back-cover blurb can be

A back cover holds far fewer words than an online description: at book-text size, roughly 250 on a 6 × 9 inch paperback and 160 on a 5 × 8, before any review quotes or author photo. Those figures are this guide's estimate, worked from the layout the site's words per page calculator uses for a book page (Palatino Linotype, 11 point, 0.75 inch margins), less two bands every back cover gives up.

The first band is the barcode. KDP's barcode requirements suggest a 2 × 1.2 inch barcode at least 0.25 inch from the trim, and when KDP adds one itself it prints it in a white box in the lower right-hand corner of the back cover, over anything underneath (KDP, hardcover cover help). With a little clear space above it, that costs about five lines of text. The second is a headline or tagline at the top, about four lines' worth in larger type.

The 12-point column scales the 11-point figures by (11 ÷ 12)², because larger type fits both fewer lines and fewer words on each. Every review quote, author bio or photo comes out of those totals. That is why a back-cover blurb is usually a cut-down version of the online description: the hook and the stakes, about 100 to 200 words, and the positioning line or list left for the online page. KDP's paperback cover rules add two limits on how small you can go: cover text at least 7 point, and kept 0.125 inch inside the trim lines.

The KDP cover size calculator gives the full wrap, the back panel and the safe lines for your page count, and the trim size chooser compares the sizes before you commit.

How to count a description before you paste it

Count the description in its source form, tags and all, because that is the text KDP counts. The order that avoids surprises:

1. Write the description as plain text and count the words in the word counter. Aim near 150 for fiction; go longer only when each added line earns its place.
2. Add the formatting, then copy the HTML source, from KDP's Source view or your own file, into the character counter. Its main figure is the characters you see, which for English text is KDP's count; it must be 4,000 or under.
3. If you also publish through IngramSpark, read the UTF-8 bytes figure: it must be 4,000 or under for the full description and 250 for the short one.
4. Paste into KDP's box and compare its own count with yours. If they differ by a few characters, look for empty brackets or invisible characters copied from a word processor; KDP's page suggests removing empty <> pairs.
5. Preview the detail page after publishing: double spaces and stray line breaks show there, not in the counter.

What this guide does not cover

This guide covers the length and the counting rules of book descriptions on Amazon KDP and IngramSpark, as their help pages stated them on 4 November 2026, and estimates how much a printed back cover holds. It is not a guide to writing copy that sells, and it does not cover A+ Content, Amazon ads, keyword selection or the limits of stores whose own help pages we could not read. Limits change; the box in each dashboard has the last word.

Simple Online Counter is a free set of browser-based counters and writing tools. Its character counter counts the characters you see, the UTF-8 bytes and four other units, and keeps the text in your browser; it is not affiliated with Amazon or IngramSpark.