The short version: a Kindle cannot open an EPUB file by itself. Every EPUB that reaches one passes through Amazon’s Send to Kindle service, which converts it on the way in. For most people, the web uploader is the whole answer: go to amazon.com/sendtokindle, drop the file in, and the book appears in your library. Email and the Kindle apps do the same job with different limits. And one route does nothing at all — copying the file over USB — which is where most failed attempts begin.
This applies to every current Kindle, from the entry-level Kindle up. If you’re still choosing a reader, note that this conversion step is a permanent feature of Kindle ownership — our Kindle buying guide weighs it in its ecosystem section. On a Kobo, the same EPUB is simply a book.
Start With the One Fact: A Kindle Can’t Open an EPUB
EPUB is the standard e-book format everywhere outside Amazon’s store — it’s what libraries, publisher stores, and most other retailers sell. A Kindle doesn’t read it natively. What Send to Kindle delivers to your device is a converted Kindle document, not the EPUB itself. Most of the time the conversion is invisible: text, chapters, and cover come through, and you’d never know the file started life in another format. Occasionally it isn’t invisible, which is what the Calibre section below is for.
That one fact explains the most common failed expectation in all of Kindle file handling: plug the Kindle into a computer, drag the EPUB into its documents folder, unplug — and nothing appears in the library. The file is sitting on the device, unread and unreadable. There is no folder trick that changes this. If the file didn’t pass through Send to Kindle (or a tool like Calibre), a Kindle will not show it to you.
The contrast is worth knowing before you blame your file: a reader with native EPUB support — a Kobo Clara BW, say — opens the same EPUB directly, no conversion, no service in between. Our Kobo vs Kindle comparison covers that file-flexibility difference in full. On a Kindle, the routes below are the way in.
Route 1: Send to Kindle for Web — Start Here
This is the default recommendation, and for most people it’s the only route they’ll ever need.
- Go to amazon.com/sendtokindle and sign in with the Amazon account your Kindle is registered to.
- Drag the EPUB onto the page, or browse your files to select it.
- Confirm the send. The converted book is delivered to your Kindle library and syncs to your device.
Limit: 200 MB per file. That is generous — an ordinary EPUB novel is a small fraction of it, and even illustrated books rarely come close. The web route handles the largest files of any Send to Kindle option, which is another reason to start here.
Best for: most people, most books, one at a time — whether your Kindle is the base model or a Paperwhite, the steps are identical.
Route 2: Email It to Your Kindle
Every Kindle has its own Send to Kindle email address. You can find yours in Manage Your Content and Devices on Amazon’s site. Files sent to that address are converted and delivered just like web uploads.
One setup step matters, and skipping it is the usual reason email sends silently fail: your sending address has to be approved first. Amazon only accepts files from email addresses you’ve added to your approved list in your account settings, as a spam and security measure. Approve the address you actually send from — your everyday email — before the first attempt.
Attachments go on a normal email; no special subject line or body text is required by the outline of the process. Limits: 50 MB total per email, and a maximum of 25 attachments.
Best for: batches of small files — a handful of short books or documents in one send — and sending from a phone, where attaching a file to an email is quicker than opening a browser tool.
Route 3: Send It From the Kindle Apps
If the EPUB already lives on your phone or tablet, you don’t need the website or an email. Share the file and choose the Kindle app as the destination; on a computer, the desktop Send to Kindle app does the same job from the other direction. Behind all of these it’s the same service: the file goes to Amazon, gets converted, and arrives in your library as a Kindle document.
Best for: files that start life on your phone — a book bought in a mobile browser, a document someone sent you — where sharing is one tap and everything else is a detour.
What Amazon Won’t Take
Three categories of file fail, and no route around the first one exists.
DRM-protected EPUBs are rejected. If an EPUB carries digital rights management, Send to Kindle’s conversion fails on it — full stop. That includes most library EPUBs downloaded as files outside the Libby flow: the file your library’s website offers for download is usually a DRM-locked EPUB, and Amazon will not convert it. There is no supported workaround, and this guide doesn’t teach DRM removal. The library route onto a Kindle runs through Libby itself, which delivers the loan in Kindle form (see the troubleshooting table below).
MOBI files are dead. Older how-tos — and there are years of them — tell you to email a .mobi file to your Kindle. That advice expired: Send to Kindle support for MOBI, and for AZW and PRC uploads, ended on December 20, 2023. MOBI files already in your library are unaffected; new uploads are refused. If a guide tells you to send a .mobi, it’s out of date.
Password-protected, corrupted, and oversized files fail. A file you can’t open without a password can’t be converted; a damaged file fails the same way; and anything over your route’s limit — 200 MB on the web, 50 MB by email — is turned away. If a send fails and the file is none of the above, it’s almost always the DRM case in disguise.
When Calibre Is the Better Tool
Send to Kindle converts what you hand it — including its flaws. If an EPUB has broken metadata, a missing or wrong cover, or messy internal formatting that the conversion garbles, the fix is to repair the file before sending: tidy the metadata, the cover, and the encoding in Calibre (the free, long-standing e-book library manager), then send the cleaned EPUB through Send to Kindle as normal.
Calibre also covers the one case Send to Kindle can’t: an older Kindle you manage by USB. Calibre converts EPUB to AZW3 — a format older Kindles read directly — and loads it onto the device over the cable, no Amazon service involved. That is the route that still works entirely offline and entirely outside your Amazon account.
Rule of thumb: one clean book → Send to Kindle. A library to repair, or an old device → Calibre.
When It Doesn’t Arrive: Troubleshooting
| Problem | What’s actually happening | The fix |
|---|---|---|
| You sent the book, but it never appears on the Kindle | The delivery is waiting on the device — or the conversion failed | Check the Kindle’s Wi-Fi connection and let it sync; then check your email inbox for a conversion-failure message from Amazon |
| The book arrives without its cover | The EPUB’s metadata, not the send, is the problem | Fix the cover in Calibre and resend the repaired file |
| A library book won’t convert | The file is DRM-protected, and Send to Kindle rejects those | Borrow it in Libby and use Libby’s Read with Kindle delivery instead |
FAQs
Does Send to Kindle cost anything?
No. The web uploader, the email route, and the app sharing all run through your Amazon account at no charge.
Does the converted book sync across my devices?
Yes. Because the book is delivered through your Amazon account rather than copied to one device, it appears in the library of your other Kindles and Kindle apps signed into the same account, with your place kept in the usual way.
Can I send PDFs the same way?
Yes — PDFs go through Send to Kindle by the same routes. One difference worth knowing: on Scribe models, PDFs keep their original layout, which is what makes margin annotation practical on the big screen.
Affiliate Disclosure: As an Amazon Associate, eReaderSearch may earn a commission from qualifying purchases made through links on this page, at no extra cost to you. This site also participates in affiliate programs for Kobo, Bookshop, and others.