What happens when you convert FB2 to MOBI
- The FB2 is converted by Calibre, the widely used open-source e-book manager, on our conversion server.
- Chapters, headings, images, the cover and the table of contents are carried over, and the text still reflows to fit any screen, because both formats are e-book formats.
- MOBI is an older Kindle format: Send to Kindle no longer accepts it, but older Kindles and the Kindle apps still read it. For a current Kindle, AZW3 or EPUB is the better choice.
- This conversion runs on our server: the file is uploaded, converted, and deleted together with the result as soon as the result has been sent back to you. Nothing is kept. Files up to 25 MB are accepted.
How to convert FB2 to MOBI online
- Press "Choose FB2 files" and select one or more files, or drag them onto the box. Files up to 25 MB each can be converted.
- There are no settings to choose: the converter keeps everything the target format can hold.
- Press "Convert to MOBI". The file is uploaded to our conversion server, converted in a few seconds, and deleted together with the result as soon as the result is sent back.
- Save each MOBI with its download button. Our server has already deleted both your FB2 and the MOBI by then.
Why convert FB2 to MOBI?
FB2 files usually come from e-books from Russian and Eastern European libraries. People convert them to MOBI because MOBI is what older Kindles and the Kindle apps read.
In short, FB2 is good at what it was made for, and MOBI is the more practical choice when the file has to open, upload or print somewhere else. FB2 opens in FBReader, Calibre and many Android reading apps, while MOBI opens on older Kindles and in the Kindle and Calibre apps.
How to convert FB2 to MOBI on Windows, Mac, iPhone and Android
On Windows
Open this page in Chrome, Edge or Firefox, drag your FB2 files in from File Explorer, and press Convert. Each MOBI is saved to your Downloads folder.
On a Mac
Safari, Chrome and Firefox all work. Drag the FB2 files from Finder onto the drop zone and the MOBI files land in Downloads.
On iPhone and iPad
Open the page in Safari and tap Choose FB2 files. You can pick from Photos or from the Files app. The converted MOBI appears in Files, in the Downloads folder.
On Android
Open the page in Chrome, tap Choose FB2 files and pick them from Files or your gallery. The MOBI is saved to the Download folder, where any file manager can find it.
Best settings for FB2 to MOBI
There are no settings: Calibre keeps the book's own styling, cover and table of contents, and the reading app decides the font size.
DRM-protected books cannot be converted. Books from Project Gutenberg, Standard Ebooks, public libraries' free collections and most independent authors are DRM-free.
FB2 vs MOBI: the differences
| FB2 | MOBI | |
|---|---|---|
| Full name | FictionBook e-book | Mobipocket e-book |
| Type | e-book | e-book |
| Created by | Russian open-source developers | Mobipocket, later Amazon |
| First released | 2004 | 2000 |
| Compression | Lossless | Lossless |
| What it holds | a book's text, structure and metadata as a single XML file | a book's text, images and table of contents |
| In a browser | opens in FBReader, Calibre and many Android reading apps | opens on older Kindles and in the Kindle and Calibre apps |
| Common uses | e-books from Russian and Eastern European libraries | older Kindle e-readers and e-books from the 2000s |
| MIME type | application/x-fictionbook+xml | application/x-mobipocket-ebook |
About FB2 and MOBI files
What is an FB2 file?
FictionBook stores a whole book as one XML file describing its structure rather than its look, so every reader lays it out its own way.
What is a MOBI file?
MOBI was the Kindle's original format. Amazon has since moved to AZW3 and KFX and no longer accepts MOBI through Send to Kindle, which now takes EPUB instead.
FB2 to MOBI not working? Common problems
- "Files up to 25 MB can be converted." Server conversions have a size limit. Compress the images in the document, or split it, and try again.
- "The conversion took too long and was stopped." Very long or complex documents can exceed the time limit. Split the document and convert the parts.
- The e-book will not convert. Books with DRM, usually those bought from Amazon or other stores, are encrypted and cannot be converted.
Convert FB2 to MOBI from the command line
This page uses Calibre. Installed on your computer, its ebook-convert command does the same conversion:
ebook-convert input.fb2 output.mobiConverting on your own computer keeps the file entirely local, which is worth it for very large or very sensitive documents. For everything else, the converter on this page does it without installing anything.
FB2 to MOBI converter FAQ
Will I lose quality converting FB2 to MOBI?
The text, images and structure are kept, and the book still reflows to fit any screen, because both are e-book formats.
Why is the MOBI a different size from the FB2?
The two formats store text and pictures differently, so the MOBI can be somewhat larger or smaller than the FB2. Images are carried over as they are.
Are my FB2 files uploaded?
Yes, for this conversion. A faithful FB2 to MOBI conversion needs Calibre, the open-source e-book manager, which cannot run in a browser. The file travels over an encrypted connection, is converted in a private temporary folder, and is deleted together with the MOBI as soon as the result has been sent back to you. We do not keep, read or share it.
Can I convert several FB2 files to MOBI at once?
Yes. Select or drop as many files as you like; they are converted one after another and each gets its own download button.
How do I open a MOBI file?
MOBI opens on older Kindles and in the Kindle and Calibre apps. MOBI is common for older Kindle e-readers and e-books from the 2000s.
Is this FB2 to MOBI converter free?
Yes. There is no sign-up and no watermark. Because this conversion uses our server, there is a fair-use limit of 25 MB per file and a number of files per hour, which stops the service being overloaded.
Can I convert FB2 to MOBI on my phone?
Yes. It works in Safari on iPhone and iPad and in Chrome on Android. The conversion happens on our server, so it is as fast on a phone as on a computer; the MOBI is saved to your Downloads folder.