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Free Online MOBI to FB2 Converter

Convert MOBI to FB2 online for free.

Drop MOBI files here
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Max file size 10MB. Sign up for more.

MOBI vs FB2: Side-by-side

Technical comparison of the two formats — useful for deciding which to use, or for confirming what changes during conversion.

Property MOBI FB2
Full name Mobipocket eBook FictionBook 2
Year introduced 2000 2004
Developer / standard body Mobipocket / Amazon FictionBook (open)
MIME type application/x-mobipocket-ebook application/x-fictionbook+xml
File extension .mobi .fb2
Compression PalmDOC compression XML (typically uncompressed)
Color / data depth N/A N/A
Max dimensions / size Software-limited Software-limited
Transparency No No
Animation No No
Standard / specification Mobipocket FictionBook (open)
Best for Older Kindle devices (replaced by AZW3 then KFX) Russian-speaking ebook community, lightweight ebook archiving

About the MOBI Format

MOBI is an ebook format originally developed by Mobipocket SA and later acquired by Amazon in 2005 for use on Kindle devices. Based on the Open eBook standard with proprietary extensions, MOBI supports reflowable content, bookmarks, annotations, and basic formatting including images, tables, and text styles. It became the primary format for personal documents and sideloaded content on Kindle eReaders, working on every Kindle model ever produced.

Amazon has since deprecated MOBI in favor of the more capable AZW3 (KF8) and KFX formats, which support enhanced typesetting, embedded fonts, and responsive layouts. As of 2022, Amazon's Send to Kindle service no longer accepts MOBI files for email delivery. However, MOBI remains widely used for legacy Kindle compatibility and is still supported by many third-party reading apps. Converting MOBI to EPUB allows reading on non-Kindle devices, while converting to AZW3 provides a modern Kindle reading experience.

MOBI to FB2 FAQ

Quick answers about compatibility, quality, metadata handling, and the most common reasons to convert MOBI files to FB2.

Can I convert MOBI books to FB2 for my Kindle or Kobo?

Yes. Upload your MOBI ebook and iFormat converts it to FB2 with chapter structure, cover art, and formatting preserved. Load the FB2 onto your Kindle, Kobo, Nook, or any eReader that supports the format.

How to convert MOBI to FB2 without losing the table of contents

Chapter navigation, the cover image, and text formatting all carry over during conversion. The FB2 has proper chapter links so you can jump between sections on your eReader just like the original MOBI.

Can I convert multiple MOBI ebooks to FB2 at once?

Yes — upload a batch of MOBI files and iFormat converts them all to FB2. Each book downloads separately or as a ZIP, so you can convert an entire library in one session.

Does the text still reflow after converting to FB2?

Yes — FB2 keeps text reflowable, so it adapts to any screen size and font setting on your eReader rather than being locked to a fixed page like a PDF.

Which reader is FB2 for?

FB2 is the FictionBook ebook format best for FictionBook readers. Convert your MOBI to FB2 when your eReader or app opens FB2 more reliably, so the whole library works on one device.

Is there a file size limit for MOBI to FB2 conversion?

The free plan supports files up to 50 MB, which covers the large majority of MOBI files. For longer or higher-resolution files, Starter raises the limit to 100 MB, Plus to 1 GB, and Pro to 5 GB.
Need the reverse conversion?
Convert FB2 back to MOBI with our companion tool.
FB2 to MOBI converter
Reviewed by Editorial team Updated