For many self-publishing authors, the journey from rough draft to finished manuscript is a labor of love. But as you approach the finish line, the creative process shifts into the logistical one. Suddenly, you are faced with acronyms like KDP, EPUB, and perhaps the most confusing of all: ISBN.
One of the most common questions new authors ask is about timing. Should you secure your identifier early in the process, or can you wait until the book is live? If you are wondering when to buy ISBN numbers for your project, the short answer is: You must buy it before you publish.
However, the “when” is more nuanced than just “before.” To ensure your book launch goes smoothly, you need to purchase your ISBN at a specific moment during your pre-production phase. This guide will walk you through the perfect timeline, the dangers of waiting too long, and why getting the timing right is crucial for your book’s success.
Before diving into the timeline, it is important to understand what you are buying. An ISBN (International Standard Book Number) is a 13-digit unique identifier for your book. It acts as a product ID for the publishing industry.
Bookstores, libraries, and online retailers use this number to track sales, manage inventory, and order stock. Without it, your book is essentially invisible to the global supply chain. While some platforms (like Amazon) offer internal tracking numbers for their specific ecosystem, an ISBN is the passport that allows your book to travel anywhere.
The ideal time to purchase your ISBN is during the book production phase, specifically before your cover design is finalized and before you format your interior file.
Here is why the specific timing matters:
Your ISBN needs to be printed inside the book. It traditionally appears on the copyright page (the back of the title page). If you wait until after you have formatted your interior to buy the number, you will have to pay your formatter to reopen the file, insert the number, and re-export the PDF. Buying it before formatting saves you time and revision fees.
This is the most practical reason to buy early. Your ISBN is used to generate the barcode that sits on the back cover of your printed book.
Buying the ISBN is only step one; registering it is step two. When you purchase an ISBN, you must log in to their system and assign that number to your specific book title. This process registers your book’s “metadata”, the title, author name, description, and price, into the Books in Print database.
It can sometimes take a few days for this data to propagate to retailers. If you buy the ISBN the night before you want to hit “publish,” you might find that retailers reject the number because their systems don’t recognize it yet. Buying it weeks in advance allows the data to settle across the network.
Technically, you cannot publish a print book without an identifier. However, some authors try to rush the process or use temporary placeholders, thinking they can “fix it later.” Here is why waiting until the last minute (or trying to add one post-publication) is a mistake.
If you publish a book using a free identifier provided by a platform like Amazon KDP, that identifier is locked to that platform. If you later decide you want to sell your book in Barnes & Noble or independent bookstores, you cannot just “add” an ISBN to the existing book.
You would essentially have to unpublish the current version and republish a new version with the new ISBN. This splits your sales rank, confuses reviews, and makes your book look unprofessional. Determining when to buy ISBN numbers is about foresight, buying it before the first copy is sold ensures your sales history remains intact under one single identity.
If you plan to set up a pre-order for your book, you will need the ISBN immediately. Retailers cannot list a product for pre-order without a unique product ID. If you wait until the book is finished to buy the number, you lose the ability to build hype and capture sales during the critical weeks leading up to your launch.
Depending on your publishing path, the urgency of when to buy ISBN blocks might shift slightly.
If you are printing paperback or hardcover books, the ISBN is non-negotiable. You should purchase it as soon as your manuscript is in the final editing stages. Do not wait for the final proofread. Once you have a working title and a confirmed author name, you are ready to buy.
Ebooks are more flexible. Major retailers like Amazon, Apple, and Barnes & Noble do not strictly require an ISBN for ebooks; they can assign their own internal tracking numbers (like the ASIN on Amazon). However, if you want your ebook distributed to libraries (via OverDrive) or smaller retailers, an ISBN is often required.
If you plan to use an aggregator like Draft2Digital or IngramSpark to send your book to hundreds of stores at once, you must own your ISBN before you even set up your account project. These platforms require a number to validate your metadata immediately.
To help you visualize the timeline, here is a standard workflow for a self-publishing author.
Many authors hesitate to buy an ISBN because of the cost (a single ISBN in the US costs $125, though they are cheaper in bulk). Platforms like Amazon KDP offer a “free ISBN.”
If you choose the free option, the question of when to buy ISBN becomes irrelevant, you get it assigned the moment you set up your title on Amazon. However, remember the golden rule: Free ISBNs are not portable. You cannot use Amazon’s free ISBN on IngramSpark.
If you plan to scale your author career, buying your own ISBN is an investment in your intellectual property. It allows you to be listed as the “Publisher of Record” rather than the retailer. If you choose to buy, you must do so before you utilize the free option, because once a book is published with a free ISBN, you can rarely switch it to a paid one without republishing the book entirely.
Publishing a book is a complex dance of creativity and administration. While it is tempting to focus solely on the writing, handling the logistics professionally is what separates a manuscript from a marketable product.
So, when to buy ISBN numbers? The answer is clear: Buy it as soon as you are committed to the title and format, but definitely before you commission your cover art or format your interior.
By securing your ISBN early, you ensure your copyright page is accurate, your barcode is professional, and your distribution channels are ready to accept your work. It is a small step in the grand scheme of writing a book, but it is the foundation upon which your book’s sales history will be built.
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