Free online CHM to MOBI converter

CHM files often contain Windows application help, while an older Kindle or another compatible reader may require MOBI. Converting the help file makes its pages available as an ebook, though interactive help features may not carry over.

What the CHM format is

CHM (Compiled HTML Help) is a compressed collection of HTML pages, images, and navigation data. Microsoft HTML Help Workshop and related help-authoring tools create CHM files, which commonly accompany Windows programs as offline manuals.

What the MOBI format is

MOBI is a legacy ebook format associated with older Kindle devices and apps. It packages reflowable text and images for reading on compatible devices; it is useful when a reader specifically accepts MOBI, but newer Kindle workflows may prefer newer formats.

How to convert CHM to MOBI

Online on 101convert.com

1. Upload the CHM file on the converter page. Several files can be added for batch conversion; the page displays the per-file size limit.
2. Set the reading device before converting.
3. Start the conversion, then download the resulting MOBI file.

The page’s conversion runs on its server with Calibre.

Offline with desktop software

Calibre is free and open-source for Windows, macOS, and Linux, and supports CHM input and MOBI output.

1. Open Calibre and choose Add books to import the CHM file.
2. Select the book, choose Convert books → Convert individually, and set the output format to MOBI.
3. Choose OK. When conversion finishes, select the book and use Save to disk to locate the output file.

For a command-line conversion, run ebook-convert input.chm output.mobi in a terminal where Calibre’s command-line tools are installed.

Quality and compatibility

CHM navigation can become an ebook table of contents, but scripts, pop-up windows, and other interactive help features do not translate into standard MOBI reading. Check the converted table of contents, links, and images, especially if the CHM is a reference manual with many separate pages. MOBI compatibility is strongest with older Kindle devices and apps; confirm that the intended reader accepts it.