# What is an EPUB cover image?

Source: https://epublab.com/glossary/cover-image/ (updated 2026-11-03)

The cover image of an EPUB 3 is the manifest item marked with the "cover-image" property; reading apps show it as the thumbnail in the library. It is usually a JPEG or PNG of the front cover.

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

A PDF has no notion of a cover: the first page may be a cover, a title page or a blank page. A converter can render the first page as the cover image, but it should not invent one, and a missing cover is not an error, just a plainer library thumbnail.