Do You Need Separate ISBNs for KDP and IngramSpark?

If you own your ISBN — purchased from Bowker or your country’s ISBN agency — you can use the same ISBN on both KDP and IngramSpark for the same book format. No separate ISBNs are needed. However, if you use a free ISBN provided by either platform, that ISBN is locked to that platform and cannot be reused elsewhere. The distinction comes down to ISBN ownership, not which printer produces your book.

How ISBNs Actually Work for Self-Published Books

An ISBN (International Standard Book Number) is a unique 13-digit identifier assigned to a specific edition and format of a book. It is the number that retailers, wholesalers, libraries, and distribution systems use to catalog and order your book. Without one, your print book cannot be listed in most bookstores or library databases.

The critical point most self-published authors miss is that an ISBN identifies the edition and format of a book — not the platform it’s sold on. A paperback edition gets one ISBN. A hardcover edition gets a different ISBN. An ebook edition gets yet another. But the same paperback sold through KDP and IngramSpark uses the same ISBN, because it’s the same product regardless of which printer fulfills the order.

This is why the question of separate ISBNs for KDP and IngramSpark is really a question about who owns the ISBN, not about the platforms themselves. If you’re new to the terminology around self-publishing, our guide to essential book publishing terms covers ISBNs alongside other key concepts.

Free vs. Purchased ISBNs: What Changes?

The biggest factor determining whether you need separate ISBNs is whether you use free platform-provided ISBNs or purchase your own from Bowker (in the US) or your national ISBN agency.

Free ISBNs come at no cost but carry restrictions. When KDP assigns you a free ISBN, that number is registered to Amazon and locked exclusively to KDP. You cannot take it to IngramSpark, Draft2Digital, or any other distributor. The same applies in reverse — IngramSpark’s free ISBN option registers the ISBN under the imprint name “Indy Pub,” not your own name or imprint, and it stays within IngramSpark’s ecosystem.

Purchased ISBNs belong to you. A Bowker ISBN registered under your name or your publishing imprint can be used on any platform, any printer, and any distributor simultaneously. You assign it once to a specific format of your book, and every platform that sells that format uses the same number. There is no platform lock-in.

The trade-off is cost. A single ISBN from Bowker costs $125. However, bulk pricing drops significantly: 10 ISBNs cost $295 (about $29.50 each), and 100 cost $575 (about $5.75 each). Some platforms resell Bowker ISBNs at a discount — KDP offers them at $99 and IngramSpark at $85 — though ISBNs purchased through a platform are still fully owned by the author. Authors in Canada get ISBNs for free through the government ISBN agency, regardless of platform.

What Are the ISBN Requirements for KDP, IngramSpark, and Draft2Digital?

Each major self-publishing platform handles ISBNs differently. Here is what each one requires and offers.

Amazon KDP

KDP offers a free ISBN for paperback and hardcover editions. This free ISBN is locked to KDP and lists Amazon as the imprint. For Kindle ebooks, an ISBN is entirely optional — Amazon uses its own ASIN identifier instead. Authors can also provide their own purchased ISBN for any format. KDP additionally resells Bowker ISBNs at $99.

IngramSpark

IngramSpark requires an ISBN for every book. It offers a free ISBN option, but the imprint is listed as “Indy Pub” rather than the author’s own imprint. IngramSpark also resells Bowker ISBNs at $85, or authors can supply their own. Because IngramSpark distributes to thousands of retailers, libraries, and wholesalers worldwide, using your own ISBN here gives you maximum flexibility.

Draft2Digital

Draft2Digital automatically assigns a free ISBN to ebooks distributed through their system. This ISBN is locked to D2D. For print books, D2D recommends using their free ISBN to avoid “Vendor of Record” conflicts if the book is already published elsewhere. Authors can also provide their own ISBN for ebook distribution.

Why Format Matters More Than Platform

The most common misconception about ISBNs is that different platforms require different ISBNs. They do not. The ISBN standard (maintained by the International ISBN Agency) ties each ISBN to a specific edition and format, not to a specific retailer or printer.

This means your paperback needs one ISBN, your hardcover needs a different ISBN, and your ebook needs a third. But if you publish your paperback on both KDP and IngramSpark using your own purchased ISBN, both platforms use the same number. The book is the same product — the printer is just a fulfillment detail.

Where confusion arises is when authors use free ISBNs. If you accept KDP’s free ISBN for your paperback, that ISBN belongs to Amazon. You then need a separate ISBN for the same paperback on IngramSpark — either IngramSpark’s free option or your own purchased one. This creates a situation where the identical physical book has two different ISBNs depending on where it’s ordered, which can cause cataloging issues in library and bookstore systems.

How Many ISBNs Do You Actually Need?

The answer depends on how many formats you plan to publish and whether you want platform independence. Here is a practical breakdown.

If you are publishing a paperback only on KDP, you need one ISBN — and KDP’s free option works fine if you don’t plan to distribute elsewhere. If you want that same paperback on both KDP and IngramSpark, you need one purchased ISBN that works on both, or two free ISBNs (one from each platform).

For authors publishing in multiple formats — say paperback, hardcover, and ebook — you need three ISBNs total. If you own all three, each one works across every platform. The 10-pack from Bowker at $295 covers multiple formats and future books, making it the most cost-effective approach for authors planning more than one title.

When setting up your book on these platforms, you’ll also want to get your Amazon KDP backend keywords right — that metadata works alongside your ISBN to make your book discoverable.

What Does ISBN Ownership Mean for Your Publishing Imprint?

Beyond platform flexibility, ISBN ownership determines the publisher of record for your book. When you use KDP’s free ISBN, Amazon appears as the publisher in industry databases like Books In Print. When you use IngramSpark’s free option, “Indy Pub” appears. Neither reflects your own author brand.

Purchasing your own ISBN lets you register a publishing imprint — a business name that appears as the publisher on your copyright page, in retailer listings, and in library catalogs. This is a professional consideration, not a vanity one. Bookstores and librarians do look at publisher names when making purchasing decisions, and a consistent imprint across all your titles signals an established publishing operation.

Your imprint name is set when you first register your ISBN with Bowker, and it applies to all ISBNs in your account. Choose it before you purchase. Along with your ISBN and imprint, decisions like choosing a trim size are part of the same setup process that defines your book’s identity in distribution systems.

Frequently Asked Questions

Can I switch from a free KDP ISBN to my own ISBN later?

No. Once a book is published on KDP with a free ISBN, that ISBN is permanently assigned. To use your own ISBN on KDP, you would need to unpublish the existing edition and create a new one with your purchased ISBN. This means losing any reviews tied to the original listing.

Do I need an ISBN for a Kindle ebook on Amazon?

No. Amazon uses its own identifier called an ASIN for Kindle ebooks, and an ISBN is entirely optional for digital publications on KDP. However, if you distribute your ebook through other platforms like Apple Books or Kobo via Draft2Digital, an ISBN is typically required.

Does using separate ISBNs on KDP and IngramSpark cause problems?

It can. When the same physical book has two different ISBNs, library and bookstore ordering systems may treat them as two different products. This can split sales data, complicate returns processing, and confuse retailers who see duplicate listings. Using one owned ISBN across both platforms avoids this entirely.

Are ISBNs free in countries outside the United States?

In some countries, yes. Canada provides ISBNs for free through Library and Archives Canada. The United Kingdom, most European countries, and Australia charge for ISBNs, though prices and agencies vary. In the US, Bowker is the sole ISBN agency, and ISBNs are never free from the agency itself — only from platforms offering their own restricted versions.

If I buy ISBNs from Bowker through KDP or IngramSpark at a discount, do I still own them?

Yes. ISBNs purchased through KDP ($99) or IngramSpark ($85) are genuine Bowker ISBNs registered to you. They are not platform-locked and can be used anywhere. The discount is simply a reseller arrangement — the ISBN ownership and flexibility are identical to buying directly from Bowker.