Convert EPUB to MOBI online for free.
Max file size 10MB. Sign up for more.
| File Name | Size | Convert To |
|---|
Checking files and selected output formats.
| File Name | File Size | Download |
|---|
A 500 KB EPUB typically becomes 550 – 600 KB as MOBI.
Quality: Text and chapter structure preserved. Some CSS styling and advanced layout from EPUB 3 may not render in MOBI.
Best for: reading on older Kindle devices that don't support EPUB natively.
Avoid when: you have a modern Kindle (post-2022) which supports EPUB directly via "Send to Kindle".
Tip: Amazon now accepts EPUB via "Send to Kindle" — MOBI is mostly obsolete unless you have a pre-2022 Kindle.
EPUB → MOBI handles side-loading books to older Kindle devices (pre-2018 Paperwhite and Oasis). Modern Kindles accept EPUB directly via the Send-to-Kindle service. Convert to MOBI only when you're side-loading via USB to an older device or when a self-publishing tool specifically wants MOBI. For anything new, EPUB or the newer AZW3 are the right choices.
MOBI is Amazon's older Kindle format, now largely superseded by AZW3 and KFX. Convert to MOBI when you need side-load compatibility with older Kindle devices (pre-2015 Paperwhite and earlier) or when a self-publishing service specifies MOBI. For modern Kindles, upload EPUB directly to Amazon KDP and let Amazon transcode.
MOBI (Mobipocket) is Amazon's older ebook format used by legacy Kindle devices. Both EPUB and MOBI contain reflowable HTML content, but MOBI uses a different packaging structure and supports a subset of CSS compared to EPUB. The conversion repackages the HTML content, converts or simplifies CSS styles, regenerates the table of contents in MOBI's format, and applies PalmDOC or HUFF/CDIC compression. Modern Kindle devices support KFX and EPUB, making MOBI increasingly obsolete.
Convert EPUB to MOBI for sideloading onto older Kindle devices (pre-2022 models) that don't support EPUB natively. Newer Kindle devices accept EPUB directly via USB or Send-to-Kindle. Amazon also recommends uploading EPUB for Kindle publishing rather than MOBI.
Technical comparison of the two formats — useful for deciding which to use, or for confirming what changes during conversion.
| Property | EPUB | MOBI |
|---|---|---|
| Full name | Electronic Publication | Mobipocket eBook |
| Year introduced | 2007 | 2000 |
| Developer / standard body | W3C (formerly IDPF) | Mobipocket / Amazon |
| MIME type | application/epub+zip | application/x-mobipocket-ebook |
| File extension | .epub | .mobi |
| Compression | ZIP-compressed XHTML + CSS | PalmDOC compression |
| Color / data depth | N/A | N/A |
| Max dimensions / size | Software-limited | Software-limited |
| Transparency | No | No |
| Animation | No | No |
| Standard / specification | W3C EPUB 3.3 / ISO/IEC 23736 | Mobipocket |
| Best for | Apple Books, Kobo, Nook, Google Play Books — reflowable text | Older Kindle devices (replaced by AZW3 then KFX) |
EPUB (Electronic Publication) is the most widely adopted open ebook standard, maintained by the W3C (formerly IDPF) and published as ISO/IEC 23736. First released in 2007 as the successor to the Open eBook format, EPUB uses XHTML for content, CSS for styling, and ZIP compression for packaging. Its defining feature is reflowable text — content automatically adapts to fit any screen size, allowing readers to adjust font size, margins, and line spacing on phones, tablets, and dedicated eReaders.
EPUB is natively supported by Apple Books, Kobo, Nook, Google Play Books, and nearly every eReader and reading app outside the Kindle ecosystem. EPUB 3, the current version, adds support for embedded fonts, SVG graphics, MathML equations, JavaScript interactivity, audio/video embedding, and comprehensive accessibility features including text-to-speech and screen reader support. While Kindle devices do not read EPUB natively, the format can be converted to MOBI or AZW3 for Kindle compatibility.
Quick answers about compatibility, quality, metadata handling, and the most common reasons to convert EPUB files to MOBI.
Read guides about PDF, Word, and editable document workflows connected to Free Online EPUB to MOBI Converter.
LinkedIn accepts PDF uploads for carousel-style document posts and resumes. Here is how to optimize them for fast loading, mobile viewing, and maximum engagement.
Convert Kindle books to EPUB for reading on Kobo, Apple Books, or any e-reader. Covers DRM-free books, format differences, and conversion tools.
A complete guide to ebook formats. Compare EPUB, MOBI, AZW3, PDF, and KFX by reader support, features, and when to use each.
Got an EPUB file and not sure how to open it? Here are the best free EPUB readers for Windows, Mac, iPhone, iPad, Android — and how to read EPUBs on a Kindle.
EPUB, PDF, and MOBI each handle ebooks differently. This guide compares reflowable text, device compatibility, DRM, and reading experience to help you pick the right format.
