EPUB, PDF, MOBI, and web reading compared

EPUB for adaptable books

EPUB packages structured publication content, metadata, navigation, styles, and assets. In a well-made reflowable EPUB, the reader can change font size, line spacing, colour theme, and margins without zooming a fixed page. That usually makes it the first choice for novels and continuous prose.

EPUB support still varies by app, especially for fixed-layout books, mathematics, audio, and scripting. Validate the file and test it in the actual reading app when accessibility or complex layout matters. The EPUB label alone does not guarantee good headings, alternative text, or navigation.

PDF for a fixed page

PDF preserves a designed page, so page numbers, diagrams, facsimiles, and print-oriented citations remain stable. It is often the honest format for a scanned historical edition or a textbook whose meaning depends on layout.

That same fixed page can be difficult on a phone. Zooming and horizontal movement interrupt reading, and an image-only scan may have no selectable text or useful screen-reader structure. Prefer a source EPUB for ordinary prose rather than automatically converting a PDF and guessing its reading order.

MOBI and web routes

MOBI is a legacy Kindle-associated format. Keep an existing lawful MOBI when an older device needs it, but for current delivery follow the device provider's supported formats and conversion guidance. Renaming EPUB to MOBI does not convert the book.

Web reading is the lowest-friction route: it can open immediately, expose source context, and avoid a local file. It may require connectivity and can change or disappear, so save the stable record URL for citation. Offline web support depends on the source and browser rather than on LibreLeaf's access label.

• Choose EPUB for adaptable text and common reader controls.
• Choose PDF when exact pages or scans matter.
• Use MOBI only for a confirmed legacy workflow.
• Use the web route for immediate reading and easy provenance.