Do you need to convert EPUB to MOBI or AZW3? The 2026 answer for Kindle

Last updated: 3 November 2026

For most people, no: you don't need to convert EPUB to MOBI for a Kindle, because Amazon's Send to Kindle service now accepts EPUB files and converts them for you. Conversion is still needed in a few cases, mainly copying books over USB or using a Kindle from before 2012. Even then, AZW3 is usually the better target than MOBI.

Does Kindle read EPUB files now?

Yes, if you deliver the EPUB through Send to Kindle. Amazon's Send to Kindle help page lists EPUB among the supported file types, alongside PDF, TXT, RTF, HTML and several image formats. Amazon converts the file on its side, and it appears in your library like any other book.

Some background helps here. Wikipedia's Kindle File Format entry says Send to Kindle used to accept only the original MOBI and AZW ebook formats. It adds that Amazon announced it would drop that support in favour of EPUB, which gets converted to AZW3 (KF8), from late 2022. That is why older guides, written when MOBI was the only route, tell you to convert first.

The word "Kindle reads EPUB" can still mislead. A Kindle doesn't open a raw EPUB file you drop onto its storage. The EPUB has to go through Amazon's conversion, which happens on Send to Kindle. If you skip that step, you still need a converted file.

When is converting EPUB to MOBI or AZW3 still necessary?

Conversion is only necessary when you can't use Send to Kindle. That's a short list, and most readers will never meet it.

Our own converter makes the same distinction. It says that Send to Kindle takes an EPUB as it is, and that you should convert only if you want to copy a book over USB. It lists AZW3 for USB copying and MOBI for Kindles from before 2012.

What about the 200 MB limit?

Amazon's pages give 200 MB per file as the Send to Kindle limit. Amazon's USB transfer guidance says the same. Most novels are far below that. Heavily illustrated books can approach it. Converting to MOBI won't help with size. Compressing images, or splitting the book into volumes, will.

Should I choose MOBI or AZW3?

Choose AZW3 unless your Kindle is very old. AZW3 (also called KF8) is the newer Kindle format and handles modern typography and layout better. MOBI is the older format. The two are easy to confuse because they share the same Kindle family history.

The "accepted by Send to Kindle" row needs a caveat. A Smallpdf guide to Kindle formats says Amazon stopped accepting new MOBI uploads and that existing MOBI books in your library still work. It advises sending the EPUB instead so Amazon can convert it to AZW3. We haven't tested every account and region, and Amazon's own page lists EPUB but not MOBI. Check Amazon's current help page if a MOBI upload behaves oddly.

So converting an EPUB to MOBI and then sending the MOBI can actually make things worse. The MOBI route may be rejected, while the original EPUB would have gone through.

How do I send an EPUB to my Kindle without converting?

Upload the EPUB through Send to Kindle for Web, the Kindle mobile app or your Send to Kindle email address. Amazon handles the rest. For a full walkthrough, see our guide on how to send an EPUB to your Kindle.

The quick version:

• Go to Amazon's Send to Kindle page and sign in.
• Drag in your EPUB, which must be 200 MB or smaller.
• Leave "Add to your library" switched on, so the book downloads to any device on your account (a setting Amazon describes on its help page).
• Choose the Kindle device or app that should receive it.
• Wait for sync. The book usually appears in your library within a few minutes, depending on connection and file size.

If you prefer email, each Kindle device and app has its own Send to Kindle address, and you attach the EPUB to a message. You must send from an email address that you've authorised in your Amazon account. That's an Amazon security setting, so check it if nothing arrives.

What if the book doesn't appear?

Check these in order:

• File size. Over 200 MB fails.
• DRM. Protected EPUBs from other stores generally can't be converted by Amazon's service. That is a rights issue, and no converter setting changes it.
• Authorised sender. Emails from addresses not on your approved list are discarded.
• Corrupt EPUB. If the file opens in no other reader either, repair or rebuild it.
• Missing table of contents. The book arrives but has no chapter menu. Our guide on fixing an EPUB with no table of contents covers it.

How do I get a good EPUB if my source is a PDF?

Convert the PDF to a reflowable EPUB, then send that EPUB. The format conversion most Kindle owners need is PDF to EPUB, not EPUB to MOBI. A PDF keeps its fixed printed page, so text stays small, and you zoom and pan to read it. Our piece on why a PDF is hard to read on a Kindle explains the problem in detail.

A good conversion should give you:

• Real chapters. A working table of contents, so you can jump between chapters on the device.
• Reflowable text. Text that resizes to your screen and font preference.
• Clean pages. No printed page numbers, watermarks or ads sitting inside the story text.
• The right device setting. Our converter offers target settings for a tablet or general reader, a 6" e-ink reader, a 7" e-ink reader and a generic e-ink screen.

Scanned PDFs are a special case. If a PDF contains page images with no text, it needs OCR, which is slow and produces text-only output. Our converter says OCR is only for scans with no text at all, and it skips the step automatically when it isn't needed. Our scanned PDF and OCR guide goes through what to expect.

Convert2EPUB can handle the PDF-to-EPUB step: the Standard model is free for text PDFs, and you can then send the EPUB straight to your Kindle.

Which route should I pick? A quick checklist

• I have an EPUB and a Kindle with Wi-Fi. Send the EPUB with Send to Kindle. Don't convert.
• I have a PDF. Convert it to EPUB for real chapters and reflowable text, then send the EPUB.
• I have a Word, text or HTML file. Convert it to EPUB, or send it directly if you accept Amazon's own handling. Fixed formatting may look different.
• I want to copy by USB. Convert to AZW3.
• My Kindle predates 2012. Convert to MOBI, and expect simpler formatting.
• I only want to read on a phone or tablet app. Most reading apps open EPUB directly, so no conversion is needed.

Whichever route you pick, keep your original EPUB. It's the most portable copy, and it works on almost every non-Kindle e-reader. You can always make a Kindle version from it later.

Frequently asked questions

Can I still convert EPUB to MOBI for my Kindle?

Yes, tools like Calibre and Kindle Previewer can still produce MOBI files, and they can be useful for very old Kindles. For a current Kindle, though, sending the EPUB through Send to Kindle is simpler. Amazon converts it for you, and recent guides report that new MOBI uploads are no longer accepted.

Is AZW3 better than MOBI?

For modern Kindles, yes. AZW3 (KF8) is the newer format and supports better layout and typography than MOBI. MOBI is mainly relevant for Kindles from before 2012.

Does Amazon change my EPUB when I send it?

Yes. Amazon converts the EPUB into a Kindle-native format, which Wikipedia describes as AZW3 (KF8). Your original file isn't altered. The converted copy is what lives in your Kindle library.

Why is my EPUB rejected or not showing on my Kindle?

The usual causes are a file over 200 MB, DRM protection, a sender email that isn't authorised in your Amazon account, or a damaged file. Work through those four, then check Amazon's Send to Kindle troubleshooting page.

Do I need to convert a PDF before sending it to a Kindle?

You can send a PDF as it is, but it keeps its fixed page layout and is awkward to read on a small screen. Converting it to EPUB first gives you reflowable text and a working table of contents. Our guide to converting a PDF to EPUB for free shows how.