Convert CHM to PDF: Fast and Simple MethodsCHM (Compiled HTML Help) files were once a standard way to distribute documentation for Windows applications. They bundle HTML pages, images, and navigation into a single compressed file. PDFs, however, are more universal, searchable, and easily printed or shared across platforms. This article covers why you might convert CHM to PDF, several fast and simple methods (including free and paid tools), step-by-step instructions, tips for preserving layout and hyperlinks, and troubleshooting common issues.
Why convert CHM to PDF?
- Portability: PDF is widely supported on Windows, macOS, Linux, mobile devices, and e-readers.
- Print-friendliness: PDFs are designed for printing and consistent page layout.
- Archiving: PDF/A and embedded fonts make PDFs better for long-term storage.
- Sharing: PDFs are easier to email and often viewed without special software.
- Search & annotation: Most PDF readers provide indexing, highlighting, and annotation tools.
Overview of methods
- Use a dedicated CHM-to-PDF converter (GUI or command-line).
- Extract CHM contents (HTML files) then print or convert to PDF using a browser or a separate HTML-to-PDF tool.
- Use a virtual PDF printer to “print” the CHM help pages to PDF.
- Batch conversion tools for multiple CHM files at once.
- Online converters (quick, but consider privacy for sensitive content).
Method 1 — Dedicated CHM-to-PDF converters (fastest for many users)
Many Windows programs are built to convert CHM directly to PDF with minimal steps. Common features include preserving table of contents, bookmarks, and images.
Steps (typical GUI tool):
- Install and launch the CHM-to-PDF converter (examples: CHM2PDF, ABC Amber CHM Converter, or other utilities).
- Open your .chm file in the app.
- Choose output settings: page size, margins, font embedding, include table of contents, and whether to preserve hyperlinks.
- Click Convert or Export to create the PDF.
Pros: simple, preserves help structure.
Cons: Windows-only tools may be required; some are paid.
Method 2 — Extract HTML from CHM, then convert
This method gives more control over content and layout and works cross-platform.
Step A — Extract CHM contents:
- Use tools like 7-Zip (some CHMs extract directly), chmlib utilities (chmextract), or “Extract It!” to unpack HTML files and assets into a folder.
Step B — Convert HTML to PDF:
- Option 1: Open the main HTML file in a modern browser (Chrome, Edge, Firefox) and use Print → Save as PDF. Adjust print settings (paper size, margins).
- Option 2: Use a dedicated HTML-to-PDF converter (wkhtmltopdf, Puppeteer, PrinceXML) for higher fidelity and command-line batch processing.
Example using wkhtmltopdf (command-line):
wkhtmltopdf path/to/index.html output.pdf Pros: cross-platform, precise control, suitable for automation.
Cons: requires extra steps; may need CSS adjustments for print layout.
Method 3 — Use a virtual PDF printer
If you can view the CHM in the Windows Help viewer or a CHM reader, you can “print” pages to a PDF printer.
Steps:
- Open the CHM file in the reader.
- Navigate to the main page or use the index.
- Select Print, choose a PDF printer driver (Microsoft Print to PDF, CutePDF, PDFCreator).
- Print all pages or selected sections to create a PDF.
Tip: Some readers support printing the entire contents; check Print Preview to confirm.
Pros: No extra conversion tools required; familiar workflow.
Cons: May not preserve bookmarks or table of contents automatically.
Method 4 — Batch conversion
For many CHM files, use batch-capable tools or scripts.
- GUI batch converters: some CHM converter tools include batch mode.
- Command-line approach: extract each CHM to a folder, then loop with wkhtmltopdf or Puppeteer to convert every index.html to a corresponding PDF. Example (bash pseudocode):
for f in *.chm; do mkdir "${f%.chm}" chmextract "$f" "${f%.chm}/" wkhtmltopdf "${f%.chm}/index.html" "${f%.chm}.pdf" done
Pros: Scales to many files; automatable.
Cons: Requires familiarity with scripting and tools.
Method 5 — Online converters
Websites offer CHM-to-PDF conversion by upload. They are convenient for one-off conversions.
Pros: No installs, quick.
Cons: Privacy concerns—don’t upload sensitive or proprietary files. File size limits may apply.
Preserving layout, table of contents, and hyperlinks
- Choose tools that explicitly support TOC/bookmarks if those are important. Some converters create PDF bookmarks from the CHM index.
- For HTML extraction + wkhtmltopdf/Puppeteer, ensure CSS includes print styles (or add custom CSS) so content flows properly across pages. Use page-break CSS rules to avoid awkward splits:
@media print { img, pre { page-break-inside: avoid; } h1, h2, h3 { page-break-before: always; } } - Embed fonts when the converter offers it to keep typography consistent.
Common issues and fixes
- Broken links to images or styles after extracting: ensure relative paths are preserved or correct them before conversion.
- Missing special characters: embed or specify UTF-8 encoding; ensure fonts support necessary glyphs.
- Very long output PDF with poor navigation: generate bookmarks from the CHM TOC or use a converter that maps headings to PDF bookmarks.
- Single-page output with compressed layout: adjust print CSS or use page-size and margin settings in your converter.
Recommended tools (summary)
- Windows GUI: CHM2PDF, ABC Amber CHM Converter (check licensing).
- Cross-platform extraction: chmlib (chmextract), 7-Zip for some CHMs.
- HTML→PDF: wkhtmltopdf (free), Puppeteer (headless Chrome), PrinceXML (commercial, high-quality).
- Virtual PDF printers: Microsoft Print to PDF (Windows ⁄11), PDFCreator.
- Online sites: convenient for small, non-sensitive files.
| Scenario | Recommended approach |
|---|---|
| Single CHM, preserve TOC/bookmarks | Dedicated CHM-to-PDF converter |
| Cross-platform, control over layout | Extract HTML → wkhtmltopdf or Puppeteer |
| Batch conversion | Scripted extraction + wkhtmltopdf |
| Quick one-off, non-sensitive | Online converter |
| Print-friendly output | Virtual PDF printer with print CSS adjustments |
Quick step-by-step example (Windows, free tools)
- Install 7-Zip and wkhtmltopdf.
- Extract CHM: right-click .chm → 7-Zip → Extract to “folder/”.
- Open the extracted folder, find the main HTML (index.html or default.htm).
- Run:
wkhtmltopdf extracted_folder/index.html output.pdf - Open output.pdf and check bookmarks/navigation. If missing, use a CHM-aware converter that maps the CHM TOC to PDF bookmarks.
Security and privacy notes
Avoid uploading private or proprietary CHM files to online services. For sensitive documentation, run conversions locally using offline tools.
Converting CHM to PDF is straightforward with several viable approaches depending on your needs: single-file convenience, batch automation, fidelity to original formatting, or cross-platform compatibility. Choose the method that matches your priorities (privacy, speed, layout control), and use the tips above to get clean, navigable PDFs from old CHM help sets.
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