Convert CHM to FB2 — Free Online Converter
Convert Compiled HTML Help (.chm) to FictionBook 2 (.fb2) online for free. Fast, secure document conversion with no watermarks or registration....
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How to Convert
Upload your .chm file by dragging it into the upload area or clicking to browse.
Choose your output settings. The default settings work great for most files.
Click Convert and download your .fb2 file when it's ready.
About CHM to FB2 Conversion
CHM to FB2 conversion transforms Microsoft Compiled HTML Help files into FictionBook format, a structured XML-based ebook format popular in Russian-language publishing and across Eastern European ebook ecosystems. FB2 organizes content into semantic sections with explicit metadata, making it ideal for ebook readers that support reflowable text with chapter-level navigation.
Our converter extracts the HTML content from the CHM archive, maps the hierarchical topic structure to FB2's section/title hierarchy, and generates well-formed FB2 XML with proper metadata, inline images, and content structure. The result is a fully functional ebook that works in FB2 readers like FBReader, CoolReader, and Moon+ Reader.
Why Convert CHM to FB2?
FB2 is the dominant ebook format in Russia and Eastern Europe, with extensive reader support on Android, iOS, and desktop platforms. Converting CHM help files to FB2 makes technical documentation accessible to users who prefer FB2-based reading workflows and devices. Many Russian-language ebook libraries and distribution platforms use FB2 exclusively.
FB2's structured XML approach also makes it an excellent intermediate format for documentation — the semantic markup (sections, titles, epigraphs, annotations) maps naturally to technical documentation's hierarchical structure, and the format can be further converted to EPUB, MOBI, or PDF.
Common Use Cases
- Converting English or Russian programming reference CHMs into FB2 for offline reading on FB2-compatible e-readers
- Making legacy software documentation available through FB2-based ebook libraries and distribution platforms
- Creating structured ebook versions of technical help files for Eastern European developer communities
- Archiving CHM help files in a well-structured XML format that is easy to parse, index, and transform
- Providing offline-readable technical references for environments where CHM viewers are not available
How It Works
FB2 (FictionBook 2) is an XML format with a defined DTD specifying document structure: description (metadata), body (content sections), and binary (base64-encoded images). Each section contains title, epigraph, and paragraph elements with inline formatting (emphasis, strong, strikethrough, code). Our pipeline extracts CHM content via decompression, parses the HTML topic tree, maps it to FB2's section hierarchy, converts HTML formatting to FB2 inline elements, base64-encodes images, and generates valid FB2 XML with proper namespace declarations.
Quality & Performance
Text content converts with excellent fidelity — paragraphs, headings, lists, and emphasis are mapped to their FB2 equivalents. Images are embedded as base64-encoded binaries within the FB2 XML. Complex HTML features (tables, multi-column layouts, JavaScript-dependent content) are simplified to linear text flow. Code blocks are preserved as code-formatted sections. The FB2 output passes validation against the FictionBook 2.0 DTD.
Device Compatibility
| Device | CHM | FB2 |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Partial | Partial |
| iPhone/iPad | Partial | Partial |
| Android | Partial | Partial |
| Linux | Partial | Partial |
| Web Browser | No | No |
Tips for Best Results
- 1Use FBReader or CoolReader on Android for the best FB2 reading experience with CHM-converted documentation
- 2Check the generated FB2 in Calibre's editor to verify structure and fix any conversion artifacts
- 3For large CHM files, the FB2 may be very long — use reader bookmarks and table of contents for navigation
- 4FB2 is an excellent intermediate step if your final target is EPUB — convert CHM → FB2 → EPUB for best results
- 5Verify images render correctly in your FB2 reader — large images may need resizing for small e-reader screens
CHM to FB2 makes Windows help file content accessible through the FictionBook ecosystem. The conversion is particularly valuable for technical documentation targeting Eastern European ebook platforms and FB2-native reading applications.