FB2 to MOBI converter
Convert FictionBook FB2 ebooks to MOBI for Kindle free online. Calibre engine, no signup required, 500 MB uploads, auto-deleted within 1 hour.
Drop a file to convert here
or click to browse
About Mobipocket eBook
Common Use Cases
- Reading FictionBook ebooks on older Kindles
- Converting Russian ebooks to Kindle format
- Sideloading FB2 content onto Kindle devices
FB2 (FictionBook 2.0) is popular in Russia and Eastern Europe, but Kindle does not support it. If you have FB2 ebooks and an older Kindle that needs MOBI files, this conversion gets your books onto the device. For newer Kindles that support AZW3 or EPUB, those formats are better choices. MOBI is best for legacy Kindle hardware.
FB2 is an XML-based ebook format with no Kindle support, while MOBI is the legacy Kindle format that older Kindle devices can read via USB sideloading.
Why Convert FB2 to MOBI?
Read FB2 books on Kindle
Kindle devices do not support FB2 at all. Converting to MOBI is the way to get your FictionBook library onto Kindle hardware, especially older models.
Use Kindle reading features
MOBI files work with Kindle bookmarks, highlights, dictionary lookup, and other reading features that are unavailable when viewing FB2 files.
Portable Kindle library
Once converted, your FB2 books sit in your Kindle library alongside your other ebooks. No separate reader app needed.
Offline Kindle reading
Sideload the MOBI via USB and read anywhere without an internet connection. Perfect for travel with an older Kindle.
When to use each
Keep as FB2 when...
- Reading in FBReader or another FB2-native app
- You want to preserve the structured XML metadata
- Using tools that process FB2 natively
- Editing or modifying the ebook content
- Your reading device supports FB2 directly
Convert to MOBI when...
- Reading on an older Kindle device
- Sideloading onto a Kindle via USB
- You want Kindle reading features like highlights
- Consolidating your library for Kindle hardware
- Your Kindle is the only device you read on
Common use cases
- Reading FictionBook ebooks on older Kindles
- Converting Russian ebooks to Kindle format
- Sideloading FB2 content onto Kindle devices
How to use
- Upload your FB2 file. Drag and drop an FB2 ebook onto the upload area, or click to browse. Maximum upload size is 500 MB.
- Start the conversion. Click the Convert File button. Calibre parses the FictionBook XML and repackages the content as a Kindle-compatible MOBI ebook.
- Download your MOBI. When processing finishes, a download link appears. Sideload the MOBI to your Kindle via USB. Files are auto-deleted within 1 hour.
Frequently asked questions
- Will Cyrillic text convert properly?
- Yes. FB2 uses UTF-8 encoding and Calibre handles Cyrillic, Latin, and other scripts without issues. Your Russian-language ebooks will convert cleanly.
- Is FB2 to MOBI conversion free?
- Yes. Free with no signup. Free users get a daily allowance, registered accounts get higher limits, and Premium or Lifetime members get unlimited conversions.
- Should I convert to MOBI or AZW3?
- AZW3 is better for Kindles from 2012 onward. Use MOBI only for first- and second-generation Kindle hardware.
- Will the table of contents work?
- Yes. Calibre builds MOBI navigation from the FB2 section structure, so chapter navigation works on your Kindle.
- What about cover images?
- If the FB2 file includes a cover image, Calibre extracts and embeds it in the MOBI output so it shows in your Kindle library.
- Is there a file size limit?
- Yes. Maximum upload size is 500 MB per conversion.
- How long are files kept on your servers?
- Uploaded and converted files are automatically deleted within 1 hour. All transfers use encrypted connections.