MOBI vs TXTZ
A detailed comparison of Mobipocket eBook and TXTZ eBook — file size, quality, compatibility, and which format to choose for your workflow.
Mobipocket eBook
eBooksMOBI 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.
About MOBI filesTXTZ eBook
eBooksTXTZ is a zipped plain text ebook format used by Calibre that packages a text file with optional metadata into a ZIP archive. It provides a lightweight ebook container when rich formatting is not required.
About TXTZ filesStrengths Comparison
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.
TXTZ Strengths
- Minimalist ebook wrapper.
- Plain-text core.
Limitations
MOBI 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.
- Proprietary container discouraged use outside Kindle.
- Effectively a legacy format — new books go to AZW3/EPUB.
TXTZ Limitations
- Niche.
- No reader adoption.
Technical Specifications
| Specification | MOBI | TXTZ |
|---|---|---|
| MIME type | application/x-mobipocket-ebook | application/x-txtz |
| Extension | .mobi, .prc (PalmDOC variant) | .txtz |
| Container | Palm Database (PDB) | ZIP + TXT |
| Markup | Compressed HTML subset | — |
| Successor | .azw, .azw3 (Kindle-specific) | — |
| Tool | — | Calibre |
Typical File Sizes
MOBI
- Text-only novel 200 KB - 1 MB
- Illustrated book 2-10 MB
TXTZ
- Novel (plain text) 200 KB - 1.5 MB
Ready to convert?
Convert between MOBI and TXTZ online, free, and without installing anything. Encrypted upload, automatic deletion after 2 hours.
Frequently Asked Questions
MOBI (Mobipocket eBook) is an ebook format designed for reading long-form text on dedicated e-readers, tablets, and ebook apps. It is part of the ebooks family and typically supports reflowable text, embedded images, chapter navigation, cover art, and metadata (title, author, ISBN) in a portable package.
TXTZ (TXTZ eBook) is an ebook format designed for reading long-form text on dedicated e-readers, tablets, and ebook apps. It is part of the ebooks family and typically supports reflowable text, embedded images, chapter navigation, cover art, and metadata (title, author, ISBN) in a portable package.
Dedicated e-readers — Kindle, Kobo, Nook, Pocketbook — support the most common ebook formats. On phones, Apple Books, Google Play Books, Moon+ Reader and KOReader all handle MOBI. For desktop reading, Calibre is the universal ebook viewer and library manager. Convert to EPUB or PDF for maximum compatibility.
Dedicated e-readers — Kindle, Kobo, Nook, Pocketbook — support the most common ebook formats. On phones, Apple Books, Google Play Books, Moon+ Reader and KOReader all handle TXTZ. For desktop reading, Calibre is the universal ebook viewer and library manager. Convert to EPUB or PDF for maximum compatibility.
Upload your MOBI to KaijuConverter and pick EPUB, MOBI, PDF, AZW3, or similar targets. Our Calibre-powered pipeline preserves chapter structure, embedded images, cover art, and metadata. Conversion takes seconds for typical novels; long technical books with many images may take a little longer.
EPUB is the open ebook standard — it plays on every e-reader except older Kindles and in every major ebook app. PDF is better for fixed-layout content (textbooks, coffee-table books) and printing. Pick EPUB when the ebook is reflowable text, PDF when the layout matters more than the reading experience.