For converting Substack newsletters to EPUB, Stack to Book is the faster, simpler option — paste a URL, download an ebook in under 60 seconds, no installation required. Calibre is better for power users who manage large ebook libraries and need advanced features like format conversion, metadata editing, and custom styling. If you just want to read a Substack on your Kindle, Stack to Book gets you there in one step. If you want to edit, customize, and organize a library of ebooks, Calibre is worth the learning curve.
Side-by-Side Comparison
| Feature | Stack to Book | Calibre |
|---|---|---|
| Price | Free | Free (open source) |
| Installation | None (browser-based) | Desktop app required |
| Substack integration | Built-in — paste URL, get book | None — manual per-post workflow |
| Full archive conversion | Automatic | Manual (post by post) |
| Conversion time | Under 60 seconds | 10-30+ minutes with setup |
| Table of contents | Auto-generated | Manual configuration |
| Output formats | EPUB | EPUB, MOBI, PDF, AZW3, and more |
| Metadata editing | Automatic | Full manual control |
| Custom styling | Standard formatting | Fully customizable CSS |
| Library management | No | Yes (main feature) |
| Ebook editing | No | Yes (built-in editor) |
| Format conversion | Substack URL to EPUB only | Any format to any format |
| Technical skill needed | None | Moderate |
When to Use Stack to Book
- You want to read a Substack newsletter on your Kindle or e-reader
- You want the whole archive as a single ebook, fast
- You don't want to install software
- You're not technical and just want it to work
- You're a Substack writer who wants to offer an ebook to subscribers
When to Use Calibre
- You manage a large ebook library and want a cataloging system
- You need to convert between many ebook formats (EPUB, MOBI, PDF, AZW3)
- You want full control over metadata, cover images, and styling
- You need to edit ebook content directly
- You're converting content from many different sources, not just Substack
The Substack Workflow: Stack to Book vs Calibre
Stack to Book
- Go to stacktobook.com
- Paste the Substack URL
- Click "Convert"
- Download the EPUB
Total time: about 60 seconds.
Calibre
- Download and install Calibre
- Navigate to each Substack post individually
- Use "Add books from URLs" or save each page as HTML
- Import into Calibre
- Configure metadata for each post
- Merge posts into a single book (or use them as separate entries)
- Convert to desired format
- Export
Total time: 15-60 minutes depending on archive size and desired customization.
Can I Use Both?
Yes. A common workflow is to use Stack to Book for the initial conversion (getting the full archive into EPUB quickly), then import the EPUB into Calibre if you want to edit metadata, change the cover, or convert to another format. Stack to Book handles the Substack-specific heavy lifting; Calibre handles the ebook management.
Frequently Asked Questions
Is Stack to Book better than Calibre for Substack?
For converting Substack specifically, yes — it's purpose-built for that task. Calibre is a general-purpose ebook tool that can do much more, but requires more effort for Substack conversion.
Can Calibre convert an entire Substack newsletter?
Not directly. Calibre has no Substack integration. You'd need to save each post individually and import them. Stack to Book fetches the entire public archive automatically.
Is Calibre free?
Yes, Calibre is free and open-source. Stack to Book is also free for basic conversions.