EPUB to MOBI Converter

How to Convert EPUB to MOBI Online

1. Upload Your EPUB File: Drag and drop your .epub file onto the page, or click "+ Add Files" to browse. Batch upload is supported — drop an entire library at once and the converter processes them in sequence. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours — no sign-up, no watermark, never shared.
2. Confirm the Output Is MOBI: MOBI is preselected since you're on the EPUB-to-MOBI page. The converter produces a classic MOBI 6 (KF7) container so the output opens on every Kindle ever shipped, including the 1st-generation Kindle (2007) and the Kindle Keyboard (2010). No extra settings are required for compatibility.
3. Review Defaults (Optional): Defaults are tuned for maximum Kindle compatibility — MOBI 6 (KF7) output, PalmDOC text compression, embedded cover image carried from the EPUB OPF manifest, and TOC rewritten from the EPUB navigation document. Most users should keep them; advanced users converting modern EPUB 3 books with embedded fonts may prefer AZW3 instead.
4. Convert and Download: Click "Convert." Each book is delivered as a .mobi file you can download individually or as a ZIP bundle. No sign-up, no email, no watermark.

Why Convert EPUB to MOBI?

Amazon retired MOBI uploads from the Send to Kindle service on December 20, 2023 and now prefers EPUB for cloud delivery, but the MOBI format itself is far from dead. Sideloading a .mobi file over USB or copying it directly into the documents/ folder of an older Kindle is still the most reliable way to load DRM-free books onto pre-2022 hardware, and many self-hosted libraries (Calibre, COPS, Kavita) continue to store MOBI as their canonical Kindle target. Common reasons readers still need this conversion:

• Sideloading to legacy Kindles — The Kindle Keyboard (3rd gen, 2010), Kindle Touch (2011), Paperwhite 1st–4th generation (2012–2018), Voyage (2014), and the basic Kindle 7th–8th gen (2014, 2016) never received the late-2022 EPUB firmware. MOBI is the only sideload format they parse cleanly.
• Libraries archived in MOBI — Calibre users who built their catalogues before 2022 frequently keep MOBI as the master Kindle format because every Kindle in the household reads it.
• DRM-free books from Project Gutenberg, Standard Ebooks, or Smashwords — These stores ship EPUB by default; converting to MOBI lets you sideload over USB without paying Amazon's "Personal Document" data fees on cellular Kindles.
• Offline reading on Kindle apps for legacy iOS / Android — Older Kindle app builds (pre-2023) still expect MOBI when files are added through file-sharing in iTunes or via the Android Kindle/ directory.
• Self-published draft review — Authors proofing manuscripts on older test devices generate MOBI alongside EPUB to confirm layout matches what Amazon's KDP pipeline produces. KDP itself now ingests EPUB and emits KFX, but reviewing on a 2016 Paperwhite requires MOBI.

Need the reverse direction or a different Kindle target? See MOBI to EPUB for modern Kindle (2022+) and most other e-readers, PDF to MOBI if you're starting from a scanned book, or EPUB to PDF for fixed-layout reading.

MOBI vs AZW3 vs KFX vs EPUB — Kindle Format Comparison

KFX is included for completeness — you cannot generate KFX directly from EPUB through any web converter because Amazon doesn't publish the spec. Books arrive as KFX only when Amazon converts them server-side for delivery.

Kindle Model Compatibility for Sideloaded MOBI

EPUB sideload support landed in firmware 5.14.2, which Amazon began rolling out in late 2022 (announced in the May 2022 transition notice). Devices that received this firmware can read EPUB natively from USB; devices that did not are MOBI-only for sideloading. Roughly:

Amazon doesn't publish a single per-model compatibility list; the cutoff above is reconstructed from MobileRead's Kindle Firmware wiki and Amazon's own May 2022 customer notification.

Frequently Asked Questions

Will Amazon's Send to Kindle email still accept MOBI in 2026?

No. Amazon stopped accepting .mobi and .azw files through Send to Kindle on December 20, 2023. Send to Kindle now accepts EPUB, PDF, DOC, DOCX, RTF, TXT, HTML, JPEG, GIF, PNG, and BMP. If you only own a modern Kindle (Paperwhite 4 onward with firmware 5.14.2+), you can skip the conversion entirely and use MOBI to EPUB for files you already own — or send the EPUB straight to your Send to Kindle address.

Which Kindle models actually still need MOBI?

Every Kindle made before 2018 — Kindle 1st gen through Paperwhite 3rd gen, Voyage, Oasis 1 and 2, Kindle Touch, and the Kindle Keyboard. These devices never received the late-2022 firmware that added native EPUB rendering, so a sideloaded EPUB will not open. MOBI remains their only practical sideload format.

Does Calibre produce a better MOBI than online tools?

Calibre's ebook-convert CLI offers more knobs — output profile (--output-profile kindle), KF8-only versus MOBI 6 + KF8, table text scaling, compression toggles — but the resulting file is structurally similar to what online converters produce. The xconvert pipeline targets the safest default: MOBI 6 (KF7), which is the version every Kindle ever shipped can parse. If you need KF8 enhancements (embedded fonts, drop caps), AZW3 is a better target than MOBI.

What's the difference between MOBI and AZW?

They are effectively the same container with different file extensions. AZW is Amazon's renamed MOBI used for DRM-protected store purchases on Kindle 1 through Kindle 3. AZW3 is a separate, newer format based on KF8 — it adds HTML5 / CSS3 support but is not what most people mean when they say "MOBI." For non-DRM sideloading, .mobi is the conventional extension.

Can I convert DRM-protected EPUB to MOBI?

No. DRM-protected EPUBs from Adobe Digital Editions, Kobo, B&N, or library lending services (OverDrive, Libby) cannot be re-encoded — removing DRM violates the terms of service of those stores and, in many jurisdictions, the DMCA. Only DRM-free EPUBs (from Project Gutenberg, Standard Ebooks, Tor.com giveaways, Humble Bundle, Smashwords' "without DRM" filter, or self-purchased Leanpub / Smashwords titles) convert successfully.

Will my cover image and table of contents survive the conversion?

Yes. The cover image embedded in the EPUB's OPF manifest becomes the MOBI cover, and the EPUB navigation document (nav.xhtml or the older toc.ncx) is rewritten into MOBI's navigation index. Chapter breaks, internal links, footnotes, and embedded images all transfer. What does not transfer cleanly: advanced CSS (custom @font-face rules, complex floats, CSS grid), MathML, JavaScript, audio/video, and EPUB 3 fixed-layout pages — MOBI 6 simply doesn't support those.

How big is the resulting MOBI file compared to the EPUB?

Usually 1.3× to 2× larger. MOBI uses PalmDOC compression for text (less efficient than EPUB's ZIP container), and images are stored uncompressed inside the MOBI record table. A 2 MB EPUB novel typically lands around 3 MB as MOBI; an illustrated EPUB at 25 MB can balloon past 40 MB. This is normal and not a sign the conversion went wrong.

Why does Amazon now prefer EPUB if MOBI was their format?

Amazon never owned the MOBI spec outright — they acquired Mobipocket in 2005 but the format was already aging by 2011, which is why they introduced KF8 (AZW3) and later KFX. Maintaining MOBI ingestion in Send to Kindle meant supporting an obsolete typography engine and rejecting EPUB-native features (proper hyphenation, modern CSS, accessibility metadata). EPUB is now the publishing industry's interchange standard, so accepting it directly reduces friction for authors and lets Amazon do the KFX conversion server-side where they control the quality.

Should I convert to MOBI or AZW3 for a 2015 Paperwhite?

Either works on a Paperwhite 3 — it was the first Paperwhite shipped with KF8 (AZW3) reader support. AZW3 gives slightly better typography (embedded fonts, drop caps). MOBI is safer if you want the same file to also work on a Kindle Keyboard or Kindle Touch in the same household. If the device is a Paperwhite 4 or newer running firmware 5.14.2+, prefer EPUB directly.