# What is a synthetic spread?

Source: https://epubcc.com/glossary/synthetic-spread/ (updated 2026-11-04)

A synthetic spread is two adjacent pages shown side by side on one screen, like an open book. In a fixed-layout EPUB the rendition:spread property says when a reading system should do it: none, landscape, or both orientations.

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

It matters for PDFs whose layout is designed in pairs, such as picture books, magazines or cookbooks with images across the gutter. Those are fixed-layout material; in a reflowable EPUB the reading app decides whether to show one or two columns, and there are no designed pages to pair.

Each page can also be pinned to the left or right side of a spread with page-spread-left or page-spread-right on its spine item; EPUBCheck reports an item that declares both as OPF-011.

How EpubCC handles it: the engine writes only reflowable EPUBs, so it never sets rendition:spread. If your PDF depends on two-page spreads, keeping the PDF is usually the better choice.