CONVERT MOBI → EPUB (MOBI to EPUB)
Convert Kindle MOBI books to open EPUB standard.
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Ghostscript + QPDFHOW TO CONVERT MOBI → EPUB
Upload the MOBI
Drop your ebook into the uploader. We detect metadata and cover art.
Convert via Calibre
Calibre parses the MOBI structure and writes an IDPF-compliant EPUB.
Download the EPUB
Grab the ebook — side-load to your reader or drop into your library.
Converting MOBI to EPUB liberates a Kindle-era ebook from the Amazon-proprietary format into the open IDPF standard every non-Kindle reader speaks. EPUB is reflowable, supports rich typography, and works natively on Kobo, Apple Books, Google Play Books, Android and iOS reading apps.
Why convert MOBI to EPUB
MOBI was Amazon's ebook container for Kindle hardware and died with Amazon's 2022 move to KFX/AZW3. Modern Kindle firmware still reads MOBI but third-party readers (Kobo, Nook, Moon+ Reader on Android) are EPUB-only. Converting ensures the book plays on every device you own now and will buy next.
MOBI vs EPUB — Technical specifications
Side-by-side comparison of the technical details.
MOBI
- MIME type
- application/x-mobipocket-ebook
- Extension
- .mobi, .prc (PalmDOC variant)
- Container
- Palm Database (PDB)
- Markup
- Compressed HTML subset
- Successor
- .azw, .azw3 (Kindle-specific)
- MIME Type
- application/x-mobipocket-ebook
- Category
- eBooks
- Full Name
- Mobipocket eBook
- Conversion Engine
- CALIBRE
EPUB
- MIME type
- application/epub+zip
- Extension
- .epub
- Container
- ZIP archive
- Markup
- XHTML 1.1 (EPUB 2); HTML5 (EPUB 3)
- MIME Type
- application/epub+zip
- Category
- eBooks
- Full Name
- EPUB eBook
- Conversion Engine
- CALIBRE
- Standards
- IDPF/W3C EPUB 2.0.1, 3.0, 3.2, 3.3
| Specification | MOBI | EPUB |
|---|---|---|
| MIME type | application/x-mobipocket-ebook | application/epub+zip |
| Extension | .mobi, .prc (PalmDOC variant) | .epub |
| Container | Palm Database (PDB) | ZIP archive |
| Markup | Compressed HTML subset | XHTML 1.1 (EPUB 2); HTML5 (EPUB 3) |
| Successor | .azw, .azw3 (Kindle-specific) | — |
| MIME Type | application/x-mobipocket-ebook | application/epub+zip |
| Category | eBooks | eBooks |
| Full Name | Mobipocket eBook | EPUB eBook |
| Conversion Engine | CALIBRE | CALIBRE |
| Standards | — | IDPF/W3C EPUB 2.0.1, 3.0, 3.2, 3.3 |
MOBI vs EPUB — Strengths and limitations
What each format does best, and where it falls short.
MOBI Strengths
- Universal Kindle support on every device ever released.
- Very small file sizes for text-heavy books.
- Mature tooling via Calibre and Amazon's KindleGen.
- Simple container structure — easy to parse.
Limitations
- Deprecated by Amazon for new uploads since 2022.
- Poor support for rich typography (drop caps, ligatures, fixed layout).
- No embedded fonts in the base format.
EPUB Strengths
- Open standard — no vendor lock-in, no DRM required.
- Reflowable text — adapts to any screen size, font size, or orientation.
- Rich typography via CSS, embedded fonts, and SVG.
- Accessibility-first: native support for screen readers, adjustable text, and alt-text.
- Universal across every non-Kindle ebook reader and library app.
Limitations
- Kindle does not support EPUB natively (Amazon wants you to convert to AZW3).
- Fixed-layout EPUBs (for children's books, comics) are awkward to author.
- Rendering quality varies between apps — some CSS works everywhere, some does not.
Quality & Compatibility
Text content transfers losslessly. Cover art, table of contents and chapter structure are preserved when the MOBI is well-formed. DRM-protected MOBI files cannot be converted — KaijuConverter respects publisher encryption.
Tips for Best Results
- For library migration, batch-convert via a single ZIP upload; the pipeline emits one EPUB per MOBI in a combined archive.
- Set output profile (Kobo, Tablet, Generic) in Advanced for reader-specific CSS tuning.
Frequently Asked Questions
Yes. The free tier accepts files up to 25 MB without registration, email capture or watermarks; paid plans go up to 2 GB. Paid plans raise the size cap, enable batch conversions and provide a REST API for automation, but nothing on the free tier is quality-limited — the output is exactly the same as on any paid plan.
Yes, provided the MOBI itself has a well-formed ToC. Calibre reads the navigation structure and writes an equivalent ToC into the EPUB. If the source lacks a ToC we can generate one from heading levels in Advanced → structure detection.
No. KaijuConverter does not strip DRM. DRM-free MOBI files — public-domain classics, self-published books, anything you authored — convert without restriction.
Uploads run over HTTPS, files are processed in isolated containers, and both the source MOBI and the EPUB output are auto-deleted within two hours. No account is required, file contents are never logged, and KaijuConverter does not use uploads for AI training. The paid plan adds a signable data-processing agreement for regulated workflows.
No. KaijuConverter does not strip digital rights management. DRM-free MOBI files — anything you authored yourself, public-domain classics, files from DRM-free retailers — convert without any restriction.
Yes, when the source MOBI has a well-formed table of contents. The chapter structure becomes navigation points in the EPUB, which reader apps use to build their ToC sidebar.
Most files finish in well under a minute. Small images and documents are typically ready in a few seconds; large video or audio files scale roughly with duration. Upload speed from your network is usually the dominant factor, not server time.
Yes. The cover is extracted from the MOBI and re-embedded in the EPUB at device-appropriate dimensions. You can also override it in Advanced by uploading a custom cover image alongside the book file.
Yes. The cover image from the MOBI is re-embedded in the EPUB at appropriate dimensions. Override in Advanced if you want to supply a different cover file.
Mobipocket eBook
Source formatMOBI is the Mobipocket eBook format historically used by Amazon Kindle devices. While Amazon has moved to newer formats, MOBI remains relevant for older Kindles and legacy eBook libraries.
EPUB eBook
Target formatEPUB is the open standard for reflowable digital books. It adapts text to any screen size and is supported by most e-readers except Kindle. EPUB 3 adds support for multimedia and interactivity.
Going the other way? Convert EPUB back to MOBI with the same engine.
Common Use Cases
Kobo and Nook reading
Non-Amazon e-ink readers accept EPUB natively and reject MOBI.
iOS and Android reading apps
Apple Books, Moon+ Reader, Aldiko and KOReader all prefer EPUB for reflow and typography.
Library portability
Converting your MOBI archive to EPUB future-proofs it against format shifts.
MOBI vs EPUB — Typical file sizes
Approximate file sizes for common scenarios.
- Text-only novel 200 KB - 1 MB
- Illustrated book 2-10 MB
- Novel (300 pages, text only) 200-800 KB
- Illustrated reference book 5-30 MB
- Fixed-layout children's book 30-100 MB
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Related comparisons
See these formats side by side to understand which fits your use case best.
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