# What is vertical writing in EPUB?

Source: https://epublab.com/glossary/vertical-writing/ (updated 2026-11-03)

Vertical writing sets text in columns from top to bottom, read right to left, as in traditional Japanese, Chinese and Korean books. EPUB 3 supports it through the CSS writing-mode property (vertical-rl).

## Why it matters when you convert a PDF to EPUB

A vertically set PDF must be read column by column from the right, which defeats converters that read line by line from the left. The EPUB then needs writing-mode in the CSS and rtl page progression.