Free KDP ISBN vs. your own ISBN

The direct answer

KDP offers a free ISBN for paperback and hardcover books (ebooks generally don't need one at all). Using it is genuinely free and simple, but it lists "Independently Published" as the publisher of record and locks that ISBN to Amazon only. Buying your own ISBN — in the US, through Bowker — makes you the publisher of record and lets you use that same ISBN to distribute through other retailers and library systems, but it costs money and is a permanent, one-time-use assignment.

What the free KDP ISBN gets you

• No cost
• Fast — assigned automatically during setup
• Available for paperback and hardcover only, not ebooks
• Publisher of record shows as "Independently Published"
• Locked to KDP — it can't be used to sell the same edition elsewhere

What buying your own gets you

• You (or your imprint) are the publisher of record
• Usable across other platforms and distributors, not just Amazon
• A real cost — pricing varies by agency and quantity; confirm current pricing directly with Bowker or your country's ISBN agency before buying
• Each format (ebook, paperback, hardcover, audiobook) needs its own separate ISBN if you're assigning your own
• Once assigned to an edition, it's permanent — it can't be reused for a different book or a substantially revised edition

Which one makes sense

The free option is reasonable if you're publishing exclusively through Amazon and don't need a personal or business imprint listed as publisher. Buying your own tends to matter more if you plan to distribute beyond Amazon (through IngramSpark, for instance), want a specific imprint name on the book, or are pursuing library or wider retail distribution. This is a decision worth making deliberately rather than defaulting to whichever option is presented first during KDP setup.

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