# Why are words split with hyphens after converting a PDF?

Source: https://epubcc.com/answers/hyphenated-words-after-pdf-conversion/ (updated 2026-11-04)

Words come out split as "conver- sion" because the PDF hyphenated them at the end of a printed line and the converter copied the line break and the hyphen as they were. A converter has to rejoin those words while keeping real hyphenated compounds such as "well-known" intact.

## Where the hyphen comes from

Typesetting software splits long words at line ends to keep the right margin even. In the PDF that split is frozen: the first half ends one line with a hyphen and the second half starts the next. On an e-reader the lines are different, so the hyphen lands in the middle of a line.

Some PDFs mark that hyphen as a soft, line-break-only hyphen; others store it as an ordinary hyphen character, which is why simple tools cannot tell the two apart.

## How EpubCC rejoins them

- When the PDF itself flags the hyphen as a line-end hyphen, the two halves are joined.
- When a line ends in "-" and the next line starts with a lowercase letter, the word is joined too.
- A hyphen followed by a capital letter or a number is kept, which protects names and ranges.
- The EPUB is then hyphenated again by the e-reader for its own line length, if you turn hyphenation on.

## What can still go wrong

A real compound broken exactly at its own hyphen at the end of a line ("state-" / "of-the-art") looks the same as a hyphenated word, so it can be joined as "stateof-the-art". The benchmark counts split and merged words per 1,000 for every engine, so you can see how often this happens on real documents.

**Can I fix split words in an EPUB I already have?** An EPUB editor with search and replace can remove "- " followed by a lowercase letter, but check each match: some are real hyphens. Converting again from the PDF is usually faster.

**Why do some e-readers add hyphens to my EPUB?** That is the reader's own hyphenation, applied to its current line length. It moves when you change the font size and can be turned off in most readers.