EPUBLabFix broken paragraphs in a PDF-to-EPUB conversion
Paragraphs break when a converter turns every line of the PDF into a line of the EPUB, because a PDF stores lines, not paragraphs. EPUBLab rebuilds paragraphs from the position of each line, rejoins hyphenated words and joins paragraphs split across pages.
Try five pages from your PDF before converting the full book.
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See the difference in reading.
Why it happens
A PDF has no notion of a paragraph. It draws lines of text at fixed positions, often with a hyphen where a word was split at the end of a line. A converter that copies those lines keeps the line breaks, and on an e-reader every line becomes a short broken paragraph.
How EPUBLab rebuilds paragraphs
- A new paragraph starts only on a real signal: a vertical gap, a change of size or weight, a first-line indent, or a line that ends early.
- Words hyphenated at the end of a line are rejoined when the PDF marks the hyphen as a line break, or when the next line starts in lowercase.
- A paragraph that doesn't end a sentence at a column or page break is joined with the next one when that one starts in lowercase.
What the benchmark shows
8-gram recall measures continuity: it drops when line joins or reading order break sentences. The table below shows the mean for each engine in our public benchmark, including the ones that beat us on some documents.
| Engine | 8-gram recall |
|---|---|
| EPUBLab engine (EPUB output) | 0.767 |
| EPUBLab engine (plain text) | 0.765 |
| pdf_oxide · extract_text | 0.726 |
| pdf_oxide · to_plain_text (XY-cut) | 0.658 |
| pdf_oxide · Markdown | 0.653 |
| PDFium · text().all() | 0.746 |
| OpenDataLoader PDF (local mode) | 0.749 |
| pdftotext (Poppler) | 0.743 |
PDFs with selectable text only. Scanned PDFs are not supported yet.
FAQ
Is it free?
Every file gets a free sample of up to 5 pages before you pay anything, so you can judge the result on your own book. The Free plan converts up to 100 pages a month; Pro and Business convert more.
Will the EPUB be perfect?
No converter can promise that, and we don't. When the engine detects problems (unreadable glyphs, doubtful reading order) it shows a warning instead of hiding it, and the sample shows you the hard parts before you pay.
Should I use Calibre instead?
If your PDF is a simple single-column text, Calibre's free converter may be enough. EPUBLab is for the hard cases: broken paragraphs, repeated headers and page numbers, footnotes, columns and chapters.