Convert EPUB to MOBI — send-to-Kindle, cover art, and the AZW3 alternative

The short version

1. Modern Kindle (Paperwhite, Oasis, Scribe, Colorsoft, Basic 2019+, Kindle app on any device)? Email the EPUB to your @kindle.com address or use the Send-to-Kindle web uploader. Amazon converts. No MOBI tool needed.
2. Original Kindle Keyboard or DX (pre-2011)? Those need .mobi. Use Calibre (free, desktop) — it's the last honest tool that still produces .mobi cleanly.
3. Format-agnostic archive? Keep EPUB — it's an open W3C standard, future-proof, and every ereader except Amazon reads it natively.
4. Send-to-Kindle rejected your EPUB? Usually a DRM error or a malformed EPUB. Re-pack the EPUB using Calibre's "Convert books" (EPUB→EPUB cleans up most issues) and try again.
5. Printing or universal compatibility? Convert EPUB to PDF with our tool. Fixed page size, works everywhere, but loses reflow.
6. DRM-protected ebook from Kindle, Kobo, Apple, Google? We can't convert it, nor can any legitimate tool. You bought a license, not a file.

What actually changed in 2022

Amazon announced the end of MOBI uploads at Send-to-Kindle on August 1, 2022. The reason: MOBI is a 20-year-old format (Mobipocket launched in 2000, Amazon acquired it in 2005) with limitations that hurt modern features — fixed-layout layouts, enhanced typography, Arabic/Hebrew script shaping, and audiobook sync. AZW3 (Kindle Format 8, 2011) and the newer KPF/KFX internal format handle these; MOBI can't.

Practically, this changes the whole ebook-to-Kindle workflow:

• 2015-2022: Convert EPUB → MOBI with Calibre, email the MOBI to your Kindle address.
• 2022-present: Email the EPUB directly. Amazon converts server-side and delivers KPF/AZW3 to your device. Or use the Send-to-Kindle web uploader, app, or browser extension.

If you're following a tutorial older than 2022 that says "convert to MOBI first," it's obsolete. Skip the conversion.

Who still needs MOBI in 2026

Short list. MOBI is the right target if you have:

• Kindle 1 (2007), Kindle 2 (2009), Kindle DX (2009-2012), Kindle Keyboard (2010-2011). These predate AZW3 (2011). MOBI is the only sideload-compatible format. Calibre is your friend.
• Non-Kindle devices that support MOBI. Some older PocketBook models, Onyx Boox on custom firmware, and a handful of Android e-reader apps list MOBI support. EPUB usually works too, making MOBI redundant.
• Archival parity. A few digital-preservation workflows want both formats for redundancy.

If your Kindle was made in 2012 or later — you don't need MOBI. Period.

The Send-to-Kindle workflow (what actually works)

Three ways to get an EPUB onto a modern Kindle, all officially supported by Amazon in 2026:

1. Email. Attach the EPUB to an email, send it to your <username>@kindle.com address (find it under Amazon → Manage Your Content and Devices → Preferences → Personal Document Settings). Amazon converts on their end, delivers in minutes. Max attachment size: 50 MB per email, 200 MB for the Kindle web uploader.
2. Send-to-Kindle web. Visit amazon.com/sendtokindle, drag the EPUB, pick destination devices. No email client needed. Free, Amazon-hosted.
3. Send-to-Kindle app (desktop) or browser extension. Right-click an EPUB on disk, "Send to Kindle." The extension adds a one-click button to Chrome/Firefox that sends whatever you're reading online.

What Amazon does server-side: re-packs the EPUB as KPF (the internal Kindle format since 2022, stored on-device as AZW3/KFX). Your cover art, TOC, metadata, and embedded fonts survive the round-trip cleanly — Amazon's converter is production-tested on millions of ebooks per day. No watermark, no DRM added (unless the source EPUB already has DRM).

Calibre: the one tool that still honestly does EPUB→MOBI

For the pre-2011-Kindle case, Calibre is the answer. It's free, open-source, offline, and the KindleGen engine (Amazon's own tool, bundled with Calibre via the integration) produces legitimate .mobi files. Install Calibre, Add books, right-click → Convert books → Output format: MOBI → Go. It handles cover, TOC, chapters, and metadata without touching DRM.

Why we're not a straightforward substitute for Calibre here: EPUB→MOBI is a specialty workflow now. The tool serves a shrinking audience (pre-2011 Kindle owners who sideload) and Calibre already does it well. We'd rather point you to the right tool than pretend to compete.

EPUB→PDF: when a fixed-layout PDF wins

Sometimes you want a PDF, not a Kindle book. Reasons:

• Printing. EPUB is reflowable — no fixed page size. PDF has page breaks.
• Non-Kindle ereader that wants PDF. Some corporate devices, e-readers with locked firmware, or PDF-only review workflows.
• Archival with layout. If page numbers and fixed layout matter for citation (legal, academic), PDF is the right archive format.
• Sharing with non-ereader users. PDF opens on every device; EPUB needs a reader app.

Our EPUB to PDF does this. Drop the .epub, pick page size (A4 or US Letter), font size, and margins, download. No upload if the file stays under our client-side size cap; larger files render server-side (deleted within an hour).

Cover art: where converters quietly drop it

EPUBs carry a cover image as an XHTML page referenced in the manifest with properties="cover-image". The conversion target has to find that reference and treat the image specially — MOBI and AZW3 have a dedicated cover metadata field; PDF's nearest equivalent is the first page.

What goes wrong: converters that grep for the first image in the EPUB (rather than reading the manifest) sometimes pick a chapter illustration as the "cover" and bury the real cover in chapter 1. Send-to-Kindle gets this right. Calibre gets this right. Cheaper converters are hit-or-miss.

Fix for a mis-extracted cover in a MOBI or AZW3: open the book in Calibre, right-click → Edit metadata → browse for the cover image → save. Re-sideload.

Metadata: TOC, author, series, language

EPUBs store metadata in package.opf — title, author, publisher, language, series, tags, ISBN. Good converters preserve all of this in the target format. The trap: language tags. A converter that defaults your language to en can break hyphenation, Arabic/Hebrew shaping, and CJK word-break rules in the output. Check after conversion; if hyphenation looks wrong, edit the metadata to set the correct BCP 47 language code.

DRM: what we won't do

A large share of the EPUB and Kindle ebooks in the world carry DRM. Kobo DRM (Adobe ADEPT), Apple Books FairPlay, Google Play Books' wrapping, and Kindle's own encryption. Legally, you're buying a license to read on approved devices — not a portable file.

Our tool (and every legitimate converter) refuses to strip DRM. If an EPUB is DRM-protected, we detect it and reject the upload with a clear error. Anyone telling you "one-click EPUB-to-MOBI with DRM removal" is either (a) lying, (b) asking you to install malware, or (c) asking you to commit a copyright violation in most jurisdictions. Don't.

What's legal: your own self-published EPUBs, books under Creative Commons or public domain, Project Gutenberg downloads, DRM-free purchases from Tor.com, Standard Ebooks, Libro.fm, itch.io, and most indie publishers.

How the options compare (honestly)

Works well / doesn't work

Works well

• Standards-compliant EPUB 2 and EPUB 3 files
• DRM-free public-domain (Project Gutenberg, Standard Ebooks)
• DRM-free indie publishers (Tor.com, Baen, Smashwords)
• Self-published manuscripts exported from Scrivener, Vellum, or Pandoc
• Simple cover art and embedded chapter images
• Standard TOC structures (navigation.xhtml or NCX)

Doesn't work (well) yet

• DRM-protected EPUBs — we reject with an error, honestly
• Fixed-layout EPUBs (children's books, comics, textbooks with custom page design) — reflow models don't carry, consider MOBI 8 or AZW3 via Calibre
• EPUBs with interactive JavaScript — Kindle ignores; PDF flattens to static
• EPUBs with embedded audio/video (EPUB 3 media overlays) — MOBI can't carry, PDF can't play
• Right-to-left languages if the target converter doesn't set the language tag — check hyphenation after

Common questions

My Kindle Paperwhite (2023) — do I need to convert to MOBI?

No. Send the EPUB via amazon.com/sendtokindle or email it to your @kindle.com address. Amazon converts server-side. Faster and cleaner than any MOBI conversion you'd do yourself.

My Kindle Keyboard (2010) — now do I need MOBI?

Yes. AZW3 (2011) isn't supported on Kindle Keyboard and older. Use Calibre (free desktop app) to convert EPUB to MOBI, then sideload via USB. Send-to-Kindle for these devices delivers the book, but the Kindle Keyboard's firmware can't render post-2011 formats, so Amazon's modern server output may render poorly. A clean MOBI sideload is safer.

Can you convert my Kindle-purchased book to EPUB?

No. Kindle purchases are DRM-protected. You hold a license to read on approved Amazon devices, not a portable file. Every legitimate converter (ours included) refuses DRM removal.

Will my cover art and TOC survive?

Via Send-to-Kindle or Calibre: yes, reliably. Via a cheap online converter: usually yes, sometimes the cover extracts from the wrong chapter image. Open the result in Calibre to spot-check and edit metadata if needed.

What about AZW3 vs MOBI vs KFX?

AZW3 (Kindle Format 8, 2011) replaced MOBI for modern Kindles and adds CSS3, embedded fonts, and fixed-layout support. KFX/KPF (2016) is Amazon's newer internal format with enhanced typography. MOBI is effectively legacy. Modern Send-to-Kindle delivers KPF; you rarely touch AZW3 or MOBI directly in 2026.

My EPUB is 80 MB — too big for Send-to-Kindle?

Probably yes over email (50 MB cap). Use the Send-to-Kindle web uploader (200 MB cap) or sideload via USB. If the EPUB is 80 MB, images are the culprit — check whether the book really needs them at full resolution, and consider re-exporting from Calibre with image downsampling on.

Can I convert EPUB to PDF instead?

Yes — use our EPUB to PDF converter. Drop the file, pick page size and margins, download. Good for printing, non-Kindle sharing, and archival with fixed layout. If the output is large, chain through our PDF compressor.

Going the other way — PDF to EPUB?

See our PDF to EPUB tool. Clean PDFs with text layers convert to readable EPUBs; column-heavy or scanned PDFs need OCR first, and single-column reflow works better than two-column academic PDFs. Expect some manual cleanup in Calibre for any complex source.

Ready?

If you have a modern Kindle: skip the conversion, email the EPUB to your @kindle.com address. Amazon converts for you, cleanly, free. If you need a PDF for print or non-Kindle sharing: our EPUB to PDF runs in the browser, free, no sign-up, no watermark. If you have a pre-2011 Kindle that needs MOBI: install Calibre, it's the right tool. For more format-strategy reading, see our Word to PDF guide and our reduce PDF file size guide. For head-to-head comparisons with paid converters, see our CloudConvert comparison.