EPUB Format Guide & Converter

Electronic Publication is an open ebook format based on HTML/CSS inside a ZIP package, introduced by IDPF / W3C (EPUB) (2007). EPUB reflows text to each screen — the standard for many ebook stores and library apps. Use EPUB for reading; convert to PDF when you need fixed page geometry for print-like handouts.

Full name

Electronic Publication

Kind

ebook

File extension

.epub

MIME type

application/epub+zip

Developer / standard

IDPF / W3C (EPUB) · 2007

Compression

none or container

Quality model

Not a pixel/sample compression format

Container

Yes — may carry multiple codecs

Common codecs

—

Technical sources

W3C: EPUB 3

Transparency

Not supported

Animation

No (still / non-animated typical use)

Typical size

Small to moderate depending on images

Browser support

Some web readers; generally opened in ebook apps

Compatibility

Works in Apple Books, Google Play Books, Kobo, Calibre, and many e-readers; Kindle often wants conversion from EPUB

EPUB compression: none or container. Lossless (or non-destructive packaging) keeps reconstructable data — size savings come from packing efficiency, not throwing detail away. Typical size profile: Small to moderate depending on images. Quality note: Great for reflowable text; fixed-layout comics are a special case

Quality: Great for reflowable text; fixed-layout comics are a special case

Typical size: Small to moderate depending on images

EPUB does not support an alpha channel. Convert to PNG, WebP, AVIF, or SVG when you need transparent backgrounds.

EPUB is a still-media or non-animated format in typical use. Use GIF, APNG, video, or animated WebP when you need motion.

Dublin Core-style package metadata: title, creator, language, identifier.

• Novels and long-form reading
• Library ebook lending formats
• Self-publishing to stores that take EPUB
• Reflowable documentation

• Pixel-identical print proofs (use PDF)
• Complex magazine layouts without fixed-layout EPUB
• Recipients who only know PDF
• Forms meant to be filled in Word

• Reflowable
• Open standard
• Supports metadata and TOC
• Good for accessibility when tagged well

• Not fixed-page by default
• Kindle often wants conversion
• CSS support varies by reader
• DRM-wrapped EPUBs restrict tooling

Works in Apple Books, Google Play Books, Kobo, Calibre, and many e-readers; Kindle often wants conversion from EPUB

Browsers: Some web readers; generally opened in ebook apps

• Calibre
• Apple Books
• Adobe Digital Editions
• Format Convertly

• E-readers, phones, tablets
• Modern desktops
• Phones and tablets with compatible apps

Open in Apple Books, Calibre, or your e-reader app. Remove DRM only when legally allowed for your copy.

Convert EPUB toward PDF when you need fixed pages, using local tools and Format Convertly paths that keep personal ebooks on-device instead of uploading them.

• Pick a target format from popular conversions or the full list below.
• Your file is read into browser memory — not uploaded to a server.
• Download the result when conversion finishes.

Incoming conversions strengthen the EPUB cluster — e.g. JPG → EPUB, PNG → EPUB.

Tools extend the format graph beyond one-off conversion — compression, metadata, and utilities for real workflows.

Uploading sensitive EPUB files to a random converter creates a third-party copy you cannot control. Format Convertly keeps processing on-device so photos, contracts, and exports stay private.