ISBN Helper

Validate your ISBN & understand when you need one.

ISBNs are confusing. This guide explains when you need a free ISBN (KDP) vs. buying your own, and validates your ISBN-13 checksum so you catch errors before upload.

ISBN-13 Validator

Paste your 13-digit ISBN to verify it's valid (checksum check).

ISBN-13 Digits only or with hyphens; we'll strip them.

Do You Need an ISBN?

📱 KDP Ebook Only

Need ISBN? No

Amazon's ASIN (Amazon Standard Identification Number) is your unique ID for ebooks. Free, automatic, works everywhere on Amazon.

📖 KDP Print

Need ISBN? Yes

Option 1: Free from KDP (Amazon-only). Option 2: Buy from Bowker ($119, works everywhere).

🌍 Going Wide

Need ISBN? Yes

Apple Books, B&N, Google Play, IngramSpark all require ISBN-13. Must buy from Bowker ($119).

📚 Print-on-Demand

Need ISBN? Yes

IngramSpark, Lightning Source don't assign ISBNs. You must provide your own from Bowker.

ISBN Myth-Busting

🚫 Myth: "I need an ISBN for Amazon ebook"

False. Amazon uses ASINs for ebooks, not ISBNs. KDP assigns a free ASIN automatically. ISBNs are for print books only.

🚫 Myth: "KDP's free ISBN works everywhere"

False. KDP's free ISBN only works on Amazon. Bookstores, libraries, and wide-distribution platforms reject it. You need Bowker's ISBN for that.

🚫 Myth: "ISBN costs $1,000"

False. Bowker (the official US ISBN authority) charges $119 for one ISBN. You don't need an ISBN to publish on Amazon KDP (free ebook or free print ISBN).

✅ Fact: "One ISBN = one version"

Each format (paperback 5x8", hardcover 6x9", ebook, audiobook) needs its own ISBN. You can't reuse the same ISBN for different versions.

Quick Decision Tree

Are you publishing ONLY on Amazon Kindle (ebook)?

→ No ISBN needed. KDP gives you a free ASIN. Move on.

Are you publishing a paperback/hardcover on KDP Print?

→ Choose one: Use KDP's free ISBN (Amazon-only) OR buy your own (for wider distribution). Can't do both.

Do you want to sell on bookstores, libraries, or IngramSpark?

→ Buy your own ISBN from Bowker ($119). KDP's free ISBN won't work.

Are you publishing multiple formats (ebook + paperback + hardcover)?

→ Budget: Each format needs its own ISBN (if print). Ebook doesn't need one (use ASIN).

Bowker ISBN Pricing (as of 2026)

Quantity	Price	Per ISBN	Best For
1 ISBN	$119	$119	One-off book
10 ISBNs	$295	$29.50	Author with 2-3 books
100 ISBNs	$575	$5.75	Prolific author (10+ books)

Check Bowker.com for current pricing. Prices update annually.