What Is a MOBI File?
MOBI is an ebook file format originally created by Mobipocket in the early 2000s and later adopted by Amazon as the native format for Kindle devices. For years, it was the standard format authors needed to publish on Kindle.
A Quick History
Amazon acquired Mobipocket in 2005 and built the Kindle ecosystem around the MOBI format. For roughly a decade, MOBI (and Amazon’s related proprietary formats) was the file type authors converted their manuscripts into for Kindle publishing.
MOBI Is Now Retired
As of March 18, 2025, Amazon no longer accepts MOBI files for new Kindle eBook uploads. KDP now requires EPUB, DOCX, or KPF instead, which Amazon converts internally into its current Kindle format. If you’re formatting a new book today, you generally don’t need a MOBI file at all.
You may still encounter MOBI files if you’re:
- Maintaining or editing an older backlist title that was originally published as MOBI
- Sideloading a book onto an older Kindle device via USB
- Working with a platform outside Amazon that still distributes in MOBI
What a MOBI File Actually Contains
Like EPUB, a MOBI file is a packaged format containing your book’s text, formatting, images, and metadata bundled together — but built on an older, more limited structure than EPUB. It supports basic reflowable text and images, but lacks EPUB 3’s support for embedded video/audio, advanced CSS styling, and modern accessibility features.
| MOBI | EPUB | |
|---|---|---|
| Status | Retired by Amazon (2025 | Current industry standard |
| Used by | Legacy Kindle devices only | Nearly all retailers and reading apps |
| Styling | Limited CSS | Full CSS3 support |
| Accessibility | Minimal | Built-in, standards-aligned |
| Multimedia | Not supported | Audio/video supported |
If you have a MOBI file and need to edit it, see our full guide to editing MOBI files. If you’re starting fresh, our EPUB 3 guide covers the format you actually need today.
Get Your File in the Right Format
Whether you’re converting a legacy MOBI file or formatting a new manuscript in EPUB, we handle the technical details so your file works correctly on every platform.
Whether you need a legacy MOBI file or a modern EPUB, see our expert ebook formatting service.