How to Send an EPUB to Kindle (Wireless & USB)

Kindle can receive an EPUB, but there is an important distinction: Amazon’s Send to Kindle service accepts EPUB and converts it for Kindle. Copying an .epub file into a Kindle’s documents folder over USB is not the same thing and may not work as expected.

This guide explains the practical ways to get an EPUB onto a Kindle: wireless Send to Kindle, USB after conversion, or a library manager that keeps those steps together.

Does Kindle read EPUB directly?

Kindle has always preferred Amazon’s own formats: AZW3, and the older MOBI before it, both descended from MobiPocket. EPUB is the open standard everyone else uses: Apple Books, Kobo, Google Play Books and most public library systems.

Amazon began accepting EPUB through Send to Kindle in 2022. In that workflow, Amazon converts the EPUB before it reaches your Kindle library. For a manual USB transfer, convert the EPUB to AZW3 first. This is also the safer option when you want to control the conversion yourself.

In short: send an EPUB wirelessly with Send to Kindle. Use AZW3 for a conventional USB transfer.

Method 1: Liber

If you do this once a year, any of the other methods is fine. If you do it every week, the manual work adds up. Liber puts conversion and sending in one step.

How it goes:

Drag the EPUB into Liber.
Pick how it travels: over USB to the connected eReader, or wirelessly through Amazon’s service (Premium, coming soon).
Hit Send to my Kindle. Liber prepares a Kindle-compatible copy first, so you are not handing the conversion to anyone else.

Both routes live in the same window, which is the point: no cable hunting for one and no email client for the other.

Method 2: USB cable

The cable is the method that fails least. It works with most Kindles whatever their firmware, and it needs no internet. The newest models connect as a media device instead of a drive, and on a Mac that takes a separate tool: the guide for any eReader covers it.

What you need:

A data cable (USB-A to Micro-USB or USB-C, depending on the model)
The file, ideally AZW3 if you’re copying it over the cable

Step by step:

Plug the Kindle into your computer with the USB cable.
It shows up as a drive, like a flash drive would.
Open it and go to the documents/ folder.
Copy the file in.
Eject the drive safely before unplugging.
The book appears in the Kindle’s library shortly after.

If you start with EPUB: convert it to AZW3 before copying it over USB. In Calibre, import the EPUB, choose Convert books, set the output to AZW3, and transfer the resulting file.

The catch: if you send books often, reaching for the cable every time gets old.

Method 3: Send to Kindle by email (wireless)

Amazon runs a service that delivers documents to your Kindle by email. Each Kindle gets its own @kindle.com address.

Setup, one time:

Go to amazon.com/myk (Manage Your Content and Devices).
Find your Kindle’s @kindle.com address under Devices → your Kindle → Send to Kindle Email.
Go to Preferences → Personal Document Settings → Approved Personal Document Email List.
Add the address you’ll be sending from.

To send a book:

Start a new email from that approved address.
Send it to your Kindle’s @kindle.com address.
The subject line doesn’t matter.
Attach the EPUB or PDF (50 MB maximum per file).
Send. The document arrives the next time the Kindle connects to a network.

Supported formats: EPUB, PDF, DOCX, HTML, RTF, among others.

Worth knowing:

You need an internet connection on both ends, the computer and the Kindle.
There’s a hard limit of 50 MB per file.
Amazon does the conversion on its servers, and it can change how the book looks.

Method 4: Send to Kindle app and browser extension

Amazon also has a Send to Kindle desktop app and browser extensions. They do the same job as the email route without making you write an email.

The browser extension is for web articles: click it and the page you’re reading goes to your Kindle.

For files, the desktop app takes drag and drop, which works well for sending a single book now and then.

Method 5: Calibre

Calibre can do all of this, it’s free, and it runs on Windows, macOS and Linux. You can use it to:

Convert between EPUB, AZW3 and MOBI
Send books wirelessly with its built-in content server
Edit metadata and cover art in depth

The steps:

Import the EPUB into Calibre.
Choose Convert books and set AZW3 as the output format.
Connect the Kindle by USB or turn on the wireless server.
Click “Send to device”.

One caveat: Calibre converts for maximum compatibility, which is why it works with almost anything, but it can also mean the typography ends up a little blunter than the original.

Where each method falls short

Every method above has a catch.

USB means finding a cable and dragging files into the right folder.
Email caps you at 50 MB and hands the conversion to Amazon, so you don’t control the result.
Calibre can do it all, but you’ll click through a lot of windows to send one book.

Liber removes all three: it picks the format for your device, sends over cable (and wirelessly once Premium arrives), and does it for a whole shelf at once instead of one book at a time. Get Liber, or first see which format suits your device.

Quick reference

If you want to…	Use
Manage your library regularly	Liber
Save web articles	The Send to Kindle browser extension
Send without an internet connection	USB cable

Frequently asked questions

Does a Kindle open an EPUB copied over USB? Better not to count on it. EPUB is meant for Send to Kindle, where Amazon accepts it and converts it during wireless delivery. If you’re copying over USB, AZW3 is the more reliable choice.

What’s the difference between AZW3 and MOBI? AZW3 (KF8) is Amazon’s current format and supports modern typesetting and CSS. MOBI is the old one, with tight limits on layout. For any Kindle from 2011 on, use AZW3.

Is there a file size limit? By email, 50 MB per document. Over USB, or through Calibre’s local server, the only limit is the free space on the Kindle.

Do I keep my highlights if I replace a file? Generally, no. Highlights are tied to the exact file on the Kindle, and if you swap it for another one, even a freshly converted copy of the same book, they stop pointing at anything. That’s why it’s best to replace a file only when it’s genuinely broken, for example with a serious formatting error.