Tested 2–5 November 2026
Best PDF to EPUB converter: eight tools tested on hard PDFs
Looking for the best PDF to EPUB converter for difficult files? We ran eight on five public-domain PDFs. epubwise was the only one that read a scanned page with no text layer, it left the fewest page numbers in the text, and all its files passed the EPUB checker. It didn't win every measure.
We make epubwise, so weigh this with that in mind. Every number below comes from the files themselves, scored by the same script for every tool, and the method and the files are listed so you can repeat the test.
The short version
- Scanned pages with no text layer: epubwise read 97.6% of the words with OCR. The other seven put pictures of the pages into the EPUB, with no text at all.
- Five of the six websites run on Calibre. The EPUB files from CloudConvert, Convertio, FreeConvert, online-convert.com and TinyWow each name Calibre as the program that made them, and FreeConvert and online-convert.com scored exactly the same as the Calibre desktop app on every file they finished.
- A 300-page scanned novel: Calibre ran for more than three hours (on a laptop that was also busy with other work) and made an 824 MB EPUB of page pictures with no text; Convertio made a 270 MB one, also pictures only. CloudConvert and FreeConvert stopped at their 5-minute free limits and online-convert.com at its 2-minute one. PDF24 broke the book into 34,758 paragraphs, many of them one word long. epubwise finished in under a minute, 1.2 MB, with the book's 35 chapters.
- Ligatures: in the CIA book, every other converter printed "efort", "frst" and "Te situation" (22, 66 and 4 times), because the PDF's character map gives each joined letter pair as its first letter only. epubwise reads the letters from the font's own glyph names and prints "effort", "first" and "The".
- Columns set close together: the 1882 magazine's columns sit 2 to 4 points apart. We checked whether each line is followed by the next line of its column: 94.0% with epubwise, 51.5% with PDF24, and under 8% with Convertio and the Calibre-based tools, whose lines from neighbouring articles run into each other. Word counts can't show this: every word can be there, in the wrong place.
- Valid files: every epubwise and PDF24 file passed EPUBCheck, the standard's own validator. Convertio's IRS file had 3,271 errors.
- Where others did as well or better: PDF24 keeps the same share of Tom Sawyer's words as we do, 99.7%. In the CIA book PDF24 has 1 split word and Convertio and TinyWow have 2 to our 3; all three of ours are the book's own dashes. The magazine's reading order is still not perfect: pages of advertisements, and one page whose columns change partway down, stay mixed.
What we measured
Each EPUB was scored by a script, not by eye, in the same way for every converter:
- Text kept: the share of the PDF's words that made it into the EPUB. Printer's notes, running heads and page footers in the PDF are left out of the count, since removing them is correct.
- Clutter left: running heads, page footers, printer's notes and stray page numbers that ended up in the middle of the reading text.
- Split words: words broken at a line end that stayed broken, like "fresh- crowned".
- Paragraphs cut short: places where a paragraph stops mid-sentence and the next one carries on in lower case.
- Contents entries in the EPUB's table of contents, and EPUB errors reported by EPUBCheck 5.4.
- Reading order (the 1882 magazine only): for neighbouring lines of a column in the PDF, how often the lower line follows the upper one in the EPUB. Only lines whose words reached that EPUB are scored.
Lower is better for everything except text kept and reading order.
Results, file by file
The Adventures of Tom Sawyer (1876 first edition, scanned)
A 300-page scan with an old OCR text layer, a running head that changes on right-hand pages, chapter headings set as engravings, and 150 illustrations. 300 pages. Source.
| Converter | Text kept | Clutter left | Split words | Paragraphs cut short | Contents entries | EPUB errors |
|---|---|---|---|---|---|---|
| epubwise | 99.7% | 0 | 8 | 49 | 36 | 0 |
| Calibre 9.13 | 0.0% page pictures only | 0 | 0 | 0 | 1 | 0 |
| CloudConvert | Stopped: free conversions are limited to 5 minutes per file | |||||
| Convertio | 0.0% page pictures only | 0 | 0 | 0 | 1 | 602 |
| FreeConvert | Stopped: free tasks are limited to 5 minutes | |||||
| online-convert.com | Stopped: free tasks are limited to 2 minutes | |||||
| PDF24 Tools | 99.7% | 84 | 78 | 27,630 | 300 | 0 |
| TinyWow | Still processing after 20 minutes, so we stopped waiting | |||||
Tom Sawyer, chapter II, as pictures only
The same book's chapter II with the text layer removed (we rendered the 7 pages as images), so a converter has to read the page itself. 7 pages. Source.
| Converter | Text kept | Clutter left | Split words | Paragraphs cut short | Contents entries | EPUB errors |
|---|---|---|---|---|---|---|
| epubwise | 97.5% | 0 | 0 | 1 | 1 | 0 |
| Calibre 9.13 | 0.0% page pictures only | 0 | 0 | 0 | 1 | 0 |
| CloudConvert | 0.0% page pictures only | 0 | 0 | 0 | 1 | 0 |
| Convertio | 0.0% page pictures only | 0 | 0 | 0 | 1 | 9 |
| FreeConvert | 0.0% page pictures only | 0 | 0 | 0 | 1 | 0 |
| online-convert.com | 0.0% page pictures only | 0 | 0 | 0 | 1 | 0 |
| PDF24 Tools | 0.0% page pictures only | 0 | 0 | 0 | 7 | 0 |
| TinyWow | 0.0% page pictures only | 0 | 0 | 0 | 1 | 2 |
Psychology of Intelligence Analysis (CIA, 1999)
A born-digital book with parts, chapters, footnotes and figures. 214 pages. Source.
| Converter | Text kept | Clutter left | Split words | Paragraphs cut short | Contents entries | EPUB errors |
|---|---|---|---|---|---|---|
| epubwise | 99.9% | 0 | 3 | 8 | 36 | 0 |
| Calibre 9.13 | 96.0% | 62 | 18 | 373 | 35 | 2 |
| CloudConvert | 96.0% | 62 | 18 | 373 | 24 | 2 |
| Convertio | 94.8% | 112 | 2 | 32 | 35 | 70 |
| FreeConvert | 96.0% | 62 | 18 | 373 | 35 | 2 |
| online-convert.com | 96.0% | 62 | 18 | 373 | 35 | 2 |
| PDF24 Tools | 93.7% | 7 | 1 | 74 | 35 | 0 |
| TinyWow | 94.8% | 112 | 2 | 32 | 35 | 42 |
IRS Publication 501 (2025)
A government publication in three narrow columns, with tables, a full-page worksheet and hidden printer's notes on every page. 31 pages. Source.
| Converter | Text kept | Clutter left | Split words | Paragraphs cut short | Contents entries | EPUB errors |
|---|---|---|---|---|---|---|
| epubwise | 99.5% | 1 | 0 | 32 | 67 | 0 |
| Calibre 9.13 | 95.6% | 32 | 269 | 347 | 66 | 1 |
| CloudConvert | 95.6% | 32 | 269 | 176 | 28 | 549 |
| Convertio | 96.2% | 62 | 6 | 1,348 | 66 | 3,271 |
| FreeConvert | 95.6% | 32 | 269 | 347 | 66 | 1 |
| online-convert.com | 95.6% | 32 | 269 | 347 | 66 | 1 |
| PDF24 Tools | 98.3% | 50 | 263 | 4,825 | 66 | 0 |
| TinyWow | 96.2% | 62 | 6 | 1,348 | 66 | 3,269 |
Scientific American, 9 December 1882
A dense magazine scan in three and four columns set only 2 to 4 points apart, with engravings and a page of tiny print. The hardest file here. 16 pages. Source.
| Converter | Text kept | Clutter left | Split words | Paragraphs cut short | Contents entries | EPUB errors |
|---|---|---|---|---|---|---|
| epubwise | 95.9% | 2 | 5 | 131 | 5 | 0 |
| Calibre 9.13 | 89.0% | 4 | 55 | 284 | 1 | 0 |
| CloudConvert | Stopped: free conversions are limited to 5 minutes per file | |||||
| Convertio | 94.0% | 20 | 36 | 1,162 | 1 | 205 |
| FreeConvert | 89.0% | 4 | 55 | 284 | 1 | 0 |
| online-convert.com | 89.0% | 4 | 55 | 284 | 1 | 0 |
| PDF24 Tools | 92.1% | 18 | 162 | 10,212 | 16 | 0 |
| TinyWow | 94.0% | 20 | 36 | 1,162 | 1 | 28 |
Reading order, lines that follow the line above them in their column: epubwise 94.0%, PDF24 Tools 51.5%, Convertio 7.4%, TinyWow 7.4%, Calibre 9.13 4.9%, FreeConvert 4.9%, online-convert.com 4.9%.
The same passage from different converters
he saw a new girl
TOM
SA
WYER.
in
the
garden
a
lovely
little
he saw a new girl in the garden a lovely little blue-eyed creature with yellow hair plaited into two long tails, white summer frock and embroidered pantalettes.
as one example of a broad class of comparable events.
32
Starting with the known facts of the
current situation and an under-standing of the unique forces
as one example of a broad class of comparable events.
Starting with the known facts of the
current situation and an understanding of the unique forces
about the nature of their craft should have no difculty with this book. Tose who are plowing virgin ground may require serious efort.
about the nature of their craft should have no difficulty with this book. Those who are plowing virgin ground may require serious effort.
This PDF sets "ffi", "Th" and "ff" as joined letters (ligatures), and its character map gives each one as its first letter only. The font's own glyph names still say which letters they are, so epubwise reads them from there. Each line is copied from the EPUB files unedited; line breaks show where a paragraph ended.
How the test was run
- epubwise: epubwise.com free plan, live server.
- Calibre 9.13: desktop app, ebook-convert with default settings.
- CloudConvert: free plan, default settings.
- Convertio: free plan, default settings.
- FreeConvert: free plan, default settings.
- online-convert.com: free plan, default settings.
- PDF24 Tools: free, default settings (Flow mode).
- TinyWow: free, default settings.
Every file was converted on 2–5 November 2026 with no account, using each tool's free tier and default settings, exactly as a visitor would. epubwise's own files were made again on 11 November 2026, after changes to our converter. On the same day we corrected the word count for Tom Sawyer: every page's running head is now left out of the PDF's words, not only the ones that read "TOM SAWYER.", which moved epubwise from 99.3% to 99.7% and PDF24 from 99.6% to 99.7%. PDF24 had changed its converter since our first run (it now takes out most stray page numbers), so its files for the CIA book, the IRS booklet and the image-only chapter are from 11 November as well; CloudConvert, Convertio and FreeConvert gave the same files again. All five PDFs are in the public domain and linked above, so anyone can run the same test. Zamzar wasn't included because its terms restrict use by competing products. We'll run the test again every three months, with the date at the top of the page.
Want to see what happens inside our converter? Read how a conversion works, try it on your own scanned PDF, or convert a PDF to EPUB now. Reading on a Kindle? Here's how to send the EPUB to it.
Questions about this comparison
Which PDF to EPUB converter is best for scanned books?
In this test only epubwise produced text from a scanned page that had no text layer; every other tool put the page pictures into the EPUB, which can't be resized or searched.
Is Calibre good for converting PDF to EPUB?
Calibre is free and fine for simple, text-only PDFs. On hard files it left page numbers in the text, split words at line ends, and took over three hours on the 300-page scan, returning pictures of the pages with no text.
Why do several online converters give the same result?
CloudConvert, Convertio, FreeConvert and online-convert.com all name Calibre as the program that made their EPUB files, so they inherit its strengths and its mistakes.
Isn't a test run by epubwise biased?
It could be, which is why the files, the settings and every measurement are listed here and the same script scores every tool. The results include the cases where another converter did better.