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EPUB vs MOBI: The Complete Guide to eBook Formats

A deep dive into the differences between EPUB and MOBI, two major eBook formats, their pros and cons, and how to choose the right format for you.

E-Ink Team2025-11-275 min read

In the digital reading era, choosing the right eBook format is crucial. EPUB and MOBI are currently the two most popular eBook formats, each with its own characteristics and use cases. This article will help you fully understand these two formats to make the best choice.

What is EPUB Format?

EPUB (Electronic Publication) is an open-standard eBook format developed and maintained by the International Digital Publishing Forum (IDPF). It is one of the most widely used eBook formats today.

Key Features of EPUB

  • Open Standard: EPUB is an open format that anyone can use for free
  • Reflowable: Content can automatically adjust layout based on screen size
  • Multimedia Support: Supports embedded images, audio, video, and more
  • Web-Based Technology: Built using HTML, CSS, and XML internally
  • Broad Compatibility: Supported by most e-readers and reading apps

Who Uses EPUB?

  • Apple Books
  • Google Play Books
  • Kobo readers
  • Most open-source readers
  • New Kindle devices (2022 and later)

What is MOBI Format?

MOBI (Mobipocket) was originally developed by Mobipocket SA and later acquired by Amazon. It is the native format for Kindle devices, now gradually being replaced by AZW3/KF8 format.

Key Features of MOBI

  • Proprietary Format: Owned and maintained by Amazon
  • DRM Support: Strong digital rights management capabilities
  • Kindle Native: Optimized specifically for Kindle devices
  • Simple Structure: Relatively simple file structure
  • Good Compression: Usually results in smaller file sizes

Who Uses MOBI?

  • Kindle devices (older versions)
  • Kindle applications
  • Some third-party readers

EPUB vs MOBI: Detailed Comparison

FeatureEPUBMOBI
Format TypeOpen StandardProprietary
File Extension.epub.mobi, .prc
Technology BaseHTML5, CSS3, XMLHTML, Proprietary Compression
Reflowable✅ Excellent✅ Good
Fixed Layout✅ Supported❌ Limited
Multimedia Support✅ Rich⚠️ Limited
Font Embedding✅ Supported⚠️ Limited
DRMOptionalMandatory
File SizeLargerSmaller
Editing DifficultyEasyDifficult

How to Choose?

When to Choose EPUB

  1. Using non-Kindle devices: If you use Apple Books, Kobo, or other e-readers, EPUB is the best choice
  2. Need flexible editing: EPUB is based on web technologies, easy to modify and customize
  3. Prefer open standards: Avoid being locked into a single platform
  4. Need complex layouts: EPUB 3 supports richer typography and multimedia features
  5. Long-term preservation: Open formats are better for long-term digital content preservation

When to Choose MOBI

  1. Using older Kindle: Pre-2022 Kindle devices natively support MOBI
  2. Sending via email to Kindle: Amazon's Send to Kindle service supports MOBI
  3. File size matters: MOBI is usually smaller than equivalent EPUB content

Format Conversion

The good news is that EPUB and MOBI can be converted to each other. Here are several common methods:

1. Using E-Ink Online Converter

Our website offers free online conversion tools, supporting:

  • EPUB to MOBI
  • HTML to EPUB
  • Markdown to EPUB

2. Using Calibre

Calibre is a powerful free eBook management software that supports conversion of almost all formats.

3. Using Kindle Previewer

Amazon's official Kindle Previewer can convert EPUB to Kindle format.

EPUB 3 vs EPUB 2

It's worth mentioning that EPUB itself has version differences:

EPUB 2

  • Based on XHTML 1.1 and CSS 2.1
  • Basic text and image support
  • Simple navigation structure

EPUB 3

  • Based on HTML5 and CSS3
  • Support for audio, video, and JavaScript
  • Enhanced accessibility features
  • Support for mathematical formulas (MathML)
  • Better multilingual support

Recommendation: If you're creating a new eBook, we strongly recommend using EPUB 3 format.

Kindle's Format Evolution

Amazon Kindle's format support has undergone significant evolution:

  1. Early Kindle (2007-2022): Primarily used MOBI/AZW formats
  2. Modern Kindle (2022-present): Began native EPUB support

This means if you have a newer Kindle device, you can read EPUB files directly without conversion!

Best Practice Recommendations

For Readers

  1. Prefer EPUB: Unless you only use older Kindle
  2. Backup original formats: Conversion may lose formatting information, keep original files
  3. Check compatibility: Confirm format compatibility with your device before purchasing or downloading

For Creators

  1. Focus on EPUB: Create eBooks in EPUB 3 format
  2. Provide multiple formats: If possible, offer both EPUB and MOBI versions
  3. Test on multiple devices: Test reading experience on different devices before publishing
  4. Use semantic markup: Use HTML tags correctly to improve accessibility

Summary

If you...Recommended Format
Use Apple BooksEPUB
Use new KindleEPUB
Use old KindleMOBI
Use KoboEPUB
Need to edit eBooksEPUB
Want universalityEPUB

In summary, EPUB is the more modern, universal, and flexible choice. As Amazon Kindle also starts supporting EPUB, this format is becoming the true industry standard.

If you have web content you want to convert to eBooks, you can use our Web to EPUB tool, converting any web page to a beautiful EPUB eBook in seconds.


Have questions or suggestions? Feel free to contact us through our website.

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