A legacy e-book format widely used for Amazon Kindle devices
The MOBI (Mobipocket) format is a legacy e-book file format originally developed by French company Mobipocket SA in 2000. Amazon acquired Mobipocket in 2005 and used MOBI as the foundation for their Kindle ecosystem, making it one of the most widely used e-book formats for many years.
MOBI files are essentially HTML content packaged in a binary container format with proprietary elements. They support basic text formatting, images, and a table of contents, with a focus on compatibility across various reading devices.
Although Amazon has largely transitioned to newer formats like AZW3 (KF8) for newer Kindle devices, MOBI remains an important format in the e-book world due to its wide compatibility with older Kindle devices and various e-reading applications.
MOBI files are constructed using a binary format based on the Palm Database (PDB) format. The files contain compressed HTML content, along with metadata, a navigation tree, and various control elements. MOBI has been largely superseded by newer formats that offer enhanced features and formatting capabilities.
MOBI's primary use case is for e-books distributed on the Amazon Kindle platform. Although newer Kindle devices support enhanced formats, MOBI remains relevant for ensuring backward compatibility with older devices and maximizing reach across the Kindle ecosystem.
Independent authors often distribute their works in MOBI format to ensure compatibility with the widest range of Kindle devices. The format's simplicity makes it accessible for DIY publishing without requiring specialized knowledge.
MOBI works well for novels, short stories, and other text-centric publications that don't rely on complex formatting or interactive elements. Its reflowable text capabilities make it suitable for content that prioritizes readability over precise layout.
Many existing e-book collections and archives use MOBI format. While new content may be created in newer formats, MOBI remains important for accessing older digital libraries and maintaining compatibility with established collections.
When publishers want to reach readers across multiple platforms without creating multiple versions, MOBI offers a reasonable compromise that works on Kindle devices while also being compatible with various third-party reading applications.
MOBI files can be read on various devices:
Several applications support MOBI reading:
MOBI has different variants with different levels of compatibility:
| Feature | MOBI | EPUB | AZW/KF8 | TXT | |
|---|---|---|---|---|---|
| Reflowable Text | |||||
| Formatting Options | |||||
| Device Support | |||||
| Interactive Features | |||||
| Open Standard | |||||
| Future-Proof |
MOBI provides good compatibility with Kindle devices but lacks the rich formatting features of newer formats like EPUB and AZW/KF8. While PDF excels at layout preservation, it lacks the adaptability of reflowable formats. TXT offers maximum compatibility but minimal features.
EPUB to MOBI is one of the most common conversions. Use Calibre or Kindle Previewer for best results. Be aware that complex formatting may be simplified, and interactive elements will be lost. Large images may be automatically resized to meet MOBI limitations.
Structure your document with proper heading styles before conversion. Create a table of contents using Word's built-in feature. Save as HTML or DOCX first, then use Calibre or similar software to convert to MOBI for best results.
PDF to MOBI conversion can be challenging. Text-based PDFs convert better than scanned documents. Expect formatting changes and possible text flow issues. Manual cleanup may be required after conversion.
MOBI to EPUB conversion works well in most cases. Use Calibre for best results. Be sure to check the metadata and cover image after conversion, as these elements may need manual adjustment.
If you're upgrading from MOBI to Amazon's newer formats, use Kindle Previewer or Calibre. This allows you to take advantage of enhanced formatting while maintaining Kindle compatibility.
Converting from MOBI to PDF creates a fixed layout from reflowable content. Consider page size, margins, and font settings for optimal readability. The resulting PDF may require manual adjustments for professional appearance.