What happens when you convert CHM to PDF
- The CHM is unpacked by 7-Zip on our conversion server, and its pages are joined into one document in the order of the help file's own table of contents.
- Scripts, style sheets, frames and embedded objects are removed, so the pages come out in a plain, readable style. Pictures stored inside the CHM are kept; anything it would load from the web is not.
- Chromium, the open-source browser behind Chrome, prints the result to PDF on A4 pages with 1 cm margins, starting each topic on a new page. Text stays selectable and searchable.
- 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 CHM to PDF online
- Press "Choose CHM 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 PDF". 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 PDF with its download button. Our server has already deleted both your CHM and the PDF by then.
Why convert CHM to PDF?
CHM files usually come from Windows help files, software manuals and some older e-books. People convert them to PDF because a PDF looks the same on every device and is what forms, portals and printers ask for.
In short, CHM is good at what it was made for, and PDF is the more practical choice when the file has to open, upload or print somewhere else. CHM opens with a double-click on Windows; a Mac or Linux PC needs an app such as Calibre or xCHM, while PDF opens in every browser's built-in viewer.
How to convert CHM to PDF on Windows, Mac, iPhone and Android
On Windows
Open this page in Chrome, Edge or Firefox, drag your CHM files in from File Explorer, and press Convert. Each PDF is saved to your Downloads folder.
On a Mac
Safari, Chrome and Firefox all work. Drag the CHM files from Finder onto the drop zone and the PDF files land in Downloads.
On iPhone and iPad
Open the page in Safari and tap Choose CHM files. You can pick from Photos or from the Files app. The converted PDF appears in Files, in the Downloads folder.
On Android
Open the page in Chrome, tap Choose CHM files and pick them from Files or your gallery. The PDF is saved to the Download folder, where any file manager can find it.
Best settings for CHM to PDF
There are no settings: every topic listed in the table of contents is included, in that order.
Topics that exist in the CHM but are missing from its table of contents may be left out, just as the help viewer never shows them.
CHM vs PDF: the differences
| CHM | ||
|---|---|---|
| Full name | Compiled HTML Help | Portable Document Format |
| Type | e-book | document |
| Created by | Microsoft | Adobe |
| First released | 1997 | 1993 |
| Compression | Lossless | Lossy or lossless |
| Transparency | n/a | No |
| Animation | n/a | No |
| Vector or raster | n/a | Vector |
| Colour | n/a | any colour, pages can mix text, vectors and images |
| What it holds | HTML pages, images, a contents tree and a search index in one compressed file | any colour, pages can mix text, vectors and images |
| In a browser | opens with a double-click on Windows; a Mac or Linux PC needs an app such as Calibre or xCHM | opens in every browser's built-in viewer |
| Common uses | Windows help files, software manuals and some older e-books | documents, forms, invoices and print-ready files |
| MIME type | application/vnd.ms-htmlhelp | application/pdf |
About CHM and PDF files
What is a CHM file?
CHM packs a whole website of help pages into one compressed file with a contents tree and search index. Windows still opens it, but blocks CHM files downloaded from the internet until you tick Unblock in their Properties, because they can run scripts.
What is a PDF file?
A PDF fixes the layout of every page so it looks the same on any device. Converting a PDF to an image renders each page to pixels; converting an image to PDF wraps it as a page.
CHM to PDF not working? Common problems
- "Files up to 25 MB can be converted." Server conversions have a size limit. Most of a large book is its pictures; a copy with smaller images will convert.
- The CHM will not open on Windows either. Windows blocks help files downloaded from the internet: right-click it, choose Properties and tick Unblock. That block does not affect converting.
- "This file is not really in CHM format." The converter checks every file before it runs anything, so a file of another format renamed to .chm is refused. Choose the page for its real format.
Convert CHM to PDF from the command line
7-Zip unpacks a CHM into the web pages inside it, which any browser opens and can print to PDF:
7z x input.chm -ohelpConverting 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.
CHM to PDF converter FAQ
Will I lose quality converting CHM to PDF?
The text, headings, lists, tables and pictures of every topic are kept. The help file's own styling and scripts are not.
Why is the PDF a different size from the CHM?
The CHM is tightly compressed, so the PDF is usually larger, especially with many pictures.
Are my CHM files uploaded?
Yes, for this conversion. A faithful CHM to PDF conversion needs 7-Zip and Chromium, two open-source tools, 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 PDF as soon as the result has been sent back to you. We do not keep, read or share it.
Can I convert several CHM files to PDF 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 PDF file?
PDF opens in every browser's built-in viewer. PDF is common for documents, forms, invoices and print-ready files.
Is this CHM to PDF 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 CHM to PDF 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 PDF is saved to your Downloads folder.