Kindle X-ray: underappreciated feature?

Today, I’ll share my thoughts on the Kindle X-ray feature and why I find it useful for both readers and writers.

X-Ray is a unique Kindle eBook feature that allows readers to learn more about a character, topic, event, place, or any other term, simply by pressing and holding on the word or phrase that interests them.

Amazon’s definition

I believe my fellow Kindle users know that highlighting a word will allow you to look it up in the built-in dictionary or show a Wikipedia definition (in the form of the very first paragraph that summarizes the topic). Kindle X-ray allows you to do the same with your custom words – characters, creatures, Sci-Fi tech, locations, whatever your imagination creates. And, it allows the reader to see where the word appears in the book – thus giving them another way to refresh something they might’ve forgotten if your story features large roster of characters and/or large world-building.

Kindle X-ray is said to have two main uses: in fiction (as I hinted above) and in scientific articles (adding definitions of new terms, for example). I’ll focus on the fiction part.

Reader’s insight

I’ve seen only a few books with X-ray enabled and even less with the feature used well – often, a sentence from the book that mentioning the character is used instead of a real description. While better than nothing, it’s still far behind what this tool can do (more on that soon).

For a complex world with many characters, what works the best is a single sentence that’ll remind the reader who/what the word/name means. It’s best used for minor characters you might not see for a while and return wondering who they are – especially if something forced you to put the book aside for a few days/weeks.

Writer’s insight

I am not idealistic enough to believe every single reader will remember every single character the moment they see them and on until the story ends. X-ray is a way to help those readers. It allows you up to 1200 characters (a paragraph or two, by my best guess) to describe the word or a phrase. They can be simple – “The killing curse” would be more than enough for Avada Kedavra from the Harry Potter universe, but it could include more information like the hand movement, the flash of green light, or the life sentence on the user.

X-ray items are divided into two categories: Characters (quite obvious) and Terms (everything else – locations, groups, companies, village names,…).


As said above, it can be a tiny encyclopedia of your own fictional world and thus help readers with keeping things straight, especially for characters and places with small appearances.

The X-ray feature can “merge” several terms for a single definition – such as only the first name, the full name, and the full name with a title – if you define it correctly. To take an example from my WIP, I could have the same X-ray item/description for “Illeana” (first name only), “Illeana Redshard” (full maiden name), “Illeana Crystelan” (full name after marriage) and “Queen Illeana Crystelan” (full name + title after marriage and coronation).


The main disadvantage is that it takes the writer’s most valuable resource: time. Unless you let it take Wikipedia’s definition (which I don’t expect to happen often in fiction), you’ll need to set up and define every item you decide to include. To use myself as an example, my WIP would mean around 50 characters (some with multiple variants, as shown above), ~10 locations, around 5 groups, a few creatures and maybe a few more items. Guesstimating the total count at 75 items and taking 5 minutes to define each (again, a guesstimate) would mean over six hours of additional work – which I can imagine many writers would not find a worthy time investment.

When and how to do it

KDP help section has articles about the X-ray feature, an user manual and a tutorial – that’s for “how”. I’ll say the basics, as I’ve understood them from the mentioned manual: some algorithm/bot will go through the manuscript and flag all words that should probably get the definition.

You, as the author, then have the choice to just accept them all and do nothing more (which will lead to the system using an excerpt where the character appears, as mentioned above) or write your own descriptions and thus use the feature’s full potential, at the cost of your time.

As for when, the advantage is that you can do it one by one, in batches, or all at once – as you choose. You can add, edit, and remove any time – but keep in mind that Kindle e-reader pre-loads this on book purchase and will refresh it when you open the book (along with popular highlights and their count), if the reader is connected to the internet. Hence, a reader who buys the book long before actually reading it might have the X-ray “encyclopedia” out of date.

It’s often suggested to upload the book to KDP in advance – so you can check for potential conversion/formatting issues and fix those before release. If you are an early bird and start this very early, you can use that time. While your book is complete and in the pre-order period, you can give some time to set up X-ray definitions. It might be a distraction from the pre-launch tasks (such as letting the world know about your book, known under the scary word ‘marketing’) to do something more related to writing. Plus, delving into it ahead will assure that the readers will have this feature working to its full potential when the book releases.

A plot twist?

Okay, I’ll admit all that I’ve written above all works under one crucial condition: you’re taking the self-published route and are in complete control of everything. However, that does not mean X-ray is limited to self-published authors. What it means is that if you want to use the feature while going the traditional route, you might need to talk with your agent/publisher about how to go about this. I can’t tell how likely they might be willing to accept such a proposal (after all, even if you prepare the definitions yourself, if they have to upload them, it’s extra work without a direct profit) but if you want to take an extra step to be reader-friendly, you might give it a try.

Also, Kindle X-ray currently supports only English language.

Closing thoughts

I hope this article shed some light on this powerful yet overlooked tool that allows an author to give the reader some extra convenience and a way to catch-up on the spot should he/she forget something. The reader in me sincerely hopes it’ll get more use but realizes the necessary time investment might prevent its growth. If you’re a writer thinking about any way to be even more reader-friendly, maybe putting the time into Kindle X-ray is something you might consider.

I’ll also welcome your questions and opinions, whether you are a reader, writer, or both. Do you (plan to) use the feature? Have you seen a book that used it well (or poorly)? Do you have anything you’d like to say about it? I’d like to know.

2 thoughts on “Kindle X-ray: underappreciated feature?

  1. Pingback: 4/2020 Writing update | Tomas, the wandering dreamer

  2. Pingback: DYI HTML e-book formatting | Tomas - the wandering dreamer

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