Guide
Amazon KDP Book Description Rules
What HTML tags KDP allows, the 50-byte backend keyword limit, the fold cut-off, and the rules Amazon quietly enforces.
KDP — Kindle Direct Publishing — accepts a small set of HTML tags in the book description field. Anything outside that allow-list is either silently stripped or breaks the fold. Most authors find this out the hard way: they paste in rich text from Word, the listing goes live, and the description is a wall of plain text with mysterious line breaks.
This guide documents the rules as Amazon's KDP help pages describe them, plus the rules Amazon quietly enforces (50-byte keyword limit, ~150 character fold cut-off, etc.). Bookmark it for your next book.
The HTML Allow-List
KDP's book description field accepts the following tags. Anything outside this list is silently stripped or breaks the rendering.
What the rules mean in practice
<a href="..."> to your author site→ stripped. The reader sees no link.<img src="..."> for a cover thumbnail→ stripped.Inline CSS for centering→ stripped. The description left-aligns.<span style="color: red">→ stripped. You get plain black text.
BookBlurb outputs only the tags in the allow-list. The fold preview shows exactly what the reader sees before “Read more.”
The Fold Cut-Off
Amazon shows the first ~150 characters of your description before the “Read more” link. What readers see on the search page is exactly those first 150 characters.
Implications:
- Your first line must earn the second.
- Your second line must establish stakes.
- Your third line must move the reader to click.
If you have a one-sentence description, that one sentence is your fold. If you have a long description, the first 150 characters are your fold.
The 7 Backend Keywords
Amazon gives you 7 keyword fields, each up to 50 bytes (not characters). Bytes ≠ characters when you include spaces or special characters.
1 field × 50 bytes = ~50 characters (if all ASCII)
What fits in 50 bytes
| Keyword | Bytes | |
|---|---|---|
cozy mystery 1940s | 19 | ✓ |
baker detective | 15 | ✓ |
historical mystery women | 26 | ✓ |
amateur sleuth baker | 21 | ✓ |
cozy mystery historical fiction baker detective | 52 | ✗ |
Wasted keyword slots
Most authors waste 2–3 of their 7 slots on words that are already in the title, subtitle, or category. Amazon de-duplicates. Don't write:
Book title: “Lisbon Nights: A Cozy Mystery”
Keyword 1: “cozy mystery” ← wasted (already in title)
Keyword 2: “lisbon nights” ← wasted (already in title)
A better use of those 2 slots:
Keyword 1: “baker detective”
Keyword 2: “1940s mystery women”
BookBlurb shows you the byte count for each keyword before you paste.
The Rules Amazon Quietly Enforces
Beyond the documented HTML allow-list, Amazon has behaviors that aren't formally documented but affect what readers see:
Stripped tags = silent
The reader sees no warning, no error, no broken HTML — just plain text where the styled text used to be.
The fold cut-off is not fixed at 150 characters
It varies by viewport and font size. Aim for ~120 characters on mobile, ~180 on desktop.
Editorial reviews render below the fold by default
To pull a review above the fold, you have to include it in your own description (which means you can't count it as a "review" for the star average).
Amazon doesn't index keyword fields as a single string
Each of the 7 fields is indexed independently. Use all 7.
What BookBlurb Does (and Doesn't)
See the rules in action
Paste your pitch and get KDP-ready HTML plus 7 keyword suggestions — free, no signup required.
Try the KDP Description Generator →Frequently Asked Questions
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