PDF to EPUB converters compared
Five tools worth knowing about, and the one question most comparisons skip: does it upload your document? Calibre gives the best results but needs installing. pdf2ereader is the only one of the five that converts in the browser without an upload. The other three are server-side, more flexible on formats, and capped on free use.
| Tool | Runs on | Uploads your file | Price and free limits | Keeps your file | Output formats | OCR |
|---|---|---|---|---|---|---|
| pdf2ereader | Your browser | No | Free, unlimited | Never has it | EPUB only | No |
| Calibre | Desktop app | No | Free, open source | Never has it | EPUB, AZW3, MOBI, PDF, DOCX, + | No (plugins exist) |
| CloudConvert | Their servers | Yes | Free: 10 conversions a day, 1 GB per file | Up to 24 hours | Very many | Yes (paid) |
| Zamzar | Their servers | Yes | Free: 2 files a day, 5 MB for PDF to EPUB | Output up to 24 hours | Very many | Yes (paid) |
| Convertio | Their servers | Yes | Free up to 1 GB per file; daily limit not published | Output up to 24 hours | Very many | Separate OCR tool |
Free limits and retention checked 7 October 2026 against each service's own pages: CloudConvert pricing, CloudConvert privacy, Zamzar size limits, Zamzar FAQ, Convertio security. They change often.
Which one should you use
Converting one book, and you'd rather not upload it: use this site. It runs in the tab, needs no account and has no size cap beyond your own browser's memory.
Converting a whole library, or you want control over the output: use Calibre. It is genuinely better at this than we are. Twenty years of work has gone into its PDF handling, it manages your library as well as converting, and it produces AZW3 and MOBI if you need them. The cost is a desktop install and an interface that takes an afternoon to get comfortable with.
You have a scan, or an unusual source format: use a server-side service with OCR, or run OCRmyPDF first and then convert the result anywhere. Nothing that runs locally in a browser will read a photograph of a page.
The upload question
It is the row most comparisons leave out, and for a book it matters more than the feature list. Uploading a document means a copy exists on someone else's hardware, subject to their retention policy and their breaches. For a shopping list that is fine. For a manuscript, a contract, a medical report or a book you paid for, it is a decision worth making deliberately.
Two of the five never receive your file. Calibre because it runs on your own computer, and this site because it has no upload endpoint at all — the conversion is JavaScript in your browser tab. You can check that claim in about a minute: open your developer tools, watch the Network tab, and convert something. Your file never appears there. Or convert one file, disconnect from the internet, and convert another.
Where this site loses
Worth stating plainly, because a comparison where the author wins every row is not a comparison.
- Calibre converts better. Especially on awkward layouts.
- EPUB only. No AZW3, no MOBI, no DOCX. A browser cannot write the Kindle container formats, and Amazon no longer accepts MOBI anyway.
- No OCR, so scans are out.
- No batch mode. One file at a time.
- Memory-bound. Very large files can exhaust the browser tab, where a server has no such limit.
Format notes for Kindle owners
Send EPUB. Send to Kindle stopped accepting MOBI on 20 December 2023, and it handles EPUB directly and converts it on their end. Any converter still steering you to MOBI is out of date, and the file will bounce. You don't need AZW3 or KFX for Send to Kindle either. The one time you do want AZW3 is USB: a Kindle can't open an EPUB copied over the cable, so convert it to AZW3 in Calibre first.
More on this in which formats a Kindle accepts and converting a PDF for your Kindle.
Questions
What is the best free PDF to EPUB converter?
Calibre produces the best conversions and is free and open source, but it's a desktop application you have to install. pdf2ereader is the best option that needs no install and no upload: it runs in the browser tab, so the file never leaves your computer. Web converters like CloudConvert and Zamzar are more flexible on formats but upload your document to their servers and cap free use.
Which PDF to EPUB converters upload my file?
CloudConvert, Zamzar, Convertio and every other server-side converter upload your document, process it on their infrastructure and keep it for a while: up to 24 hours at CloudConvert, and the converted output for up to 24 hours at Zamzar and Convertio, by their own policies. Calibre and pdf2ereader do not: Calibre runs on your own machine, and pdf2ereader runs in your browser with no upload endpoint to send anything to.
Is Calibre better than an online PDF to EPUB converter?
For conversion quality, usually yes. Calibre has had twenty years of work on its PDF input engine and offers far more control over the output. The trade is that it is a desktop install and a fairly dense interface. For a single book, a browser converter is quicker; for a library, Calibre is worth learning.
Do any of these handle scanned PDFs?
Only the paid tiers of the server-side services, which run OCR. A scan contains photographs of pages rather than text, so there is nothing to extract without it. Neither Calibre nor pdf2ereader does OCR. Run the file through OCRmyPDF or Acrobat first, then convert the result.
Why does the format matter for a Kindle?
Send to Kindle stopped accepting MOBI on 20 December 2023 and takes EPUB directly, converting it on their end. Any converter still offering MOBI as the Kindle option is working from old information, and a file made that way will be rejected. The exception is USB: a Kindle opens AZW3 and MOBI natively but not EPUB, so a book you sideload has to be converted to AZW3 first, which Calibre does.
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