RTF (Rich Text Format) is a document format used to store paginated text, with optional formatting, tables, images, hyperlinks, headers and footers. It sits in the documents & text family and is typically associated with a specific office suite or publishing pipeline that defined the format and ships the canonical reader.

EPUB vs RTF — Differences, File Size & When to Use Each

EPUB vs RTF

A detailed comparison of EPUB eBook and Rich Text Format — file size, quality, compatibility, and which format to choose for your workflow.

Convert RTF → EPUB

EPUB

EPUB eBook

eBooks

EPUB is the open standard for reflowable digital books. It adapts text to any screen size and is supported by most e-readers except Kindle. EPUB 3 adds support for multimedia and interactivity.

About EPUB files

RTF

Rich Text Format

Documents & Text

RTF is a cross-platform document format that supports basic text formatting like bold, italic, fonts, and colors. It is readable by virtually all word processors, making it useful for maximum compatibility.

About RTF files

Strengths Comparison

EPUB Strengths

Open standard — no vendor lock-in, no DRM required.
Reflowable text — adapts to any screen size, font size, or orientation.
Rich typography via CSS, embedded fonts, and SVG.
Accessibility-first: native support for screen readers, adjustable text, and alt-text.
Universal across every non-Kindle ebook reader and library app.

RTF Strengths

Plain ASCII — portable, grep-able, and diff-friendly.
Supported by every word processor on every OS since 1990.
Cannot carry macros or embedded code — relatively safe to open.
Simple enough to parse by hand or generate with a small script.
Good interchange format when DOCX compatibility is shaky.

Limitations

EPUB Limitations

Kindle does not support EPUB natively (Amazon wants you to convert to AZW3).
Fixed-layout EPUBs (for children's books, comics) are awkward to author.
Rendering quality varies between apps — some CSS works everywhere, some does not.
Adobe DRM (ADEPT) or Apple FairPlay are optional layers that complicate portability.

RTF Limitations

Frozen in 2008 — no modern features (no comments, poor styles, no track changes).
File sizes are bigger than DOCX for the same content (no compression).
Images are base64-encoded inline, inflating files further.
Visual fidelity drifts between Word versions despite the spec.

Technical Specifications

Specification	EPUB	RTF
MIME type	application/epub+zip	application/rtf
Extension	.epub	—
Container	ZIP archive	—
Markup	XHTML 1.1 (EPUB 2); HTML5 (EPUB 3)	—
Standards	IDPF/W3C EPUB 2.0.1, 3.0, 3.2, 3.3	—
Extensions	—	.rtf
Standard	—	RTF Specification 1.9.1 (2008)
Character set	—	ASCII with Unicode escapes (\u)

Typical File Sizes

EPUB

Novel (300 pages, text only) 200-800 KB
Illustrated reference book 5-30 MB
Fixed-layout children's book 30-100 MB

RTF

Short formatted letter 15-50 KB
20-page report with styling 150 KB - 1 MB
Document with embedded images 2-20 MB

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Frequently Asked Questions

EPUB (Electronic Publication) is the open standard eBook format maintained by the W3C. It supports reflowable text that adapts to screen size, embedded fonts, images, and interactive content, making it the most widely supported eBook format globally.

RTF (Rich Text Format) is a document format used to store paginated text, with optional formatting, tables, images, hyperlinks, headers and footers. It sits in the documents & text family and is typically associated with a specific office suite or publishing pipeline that defined the format and ships the canonical reader.

EPUB files open in Apple Books, Google Play Books, Calibre (free), Kobo eReaders, and Adobe Digital Editions. Note that Amazon Kindle does not natively support EPUB, so conversion to MOBI or AZW3 is needed.

Modern office suites — Microsoft Word, Google Docs, LibreOffice Writer, Apple Pages — open most RTF files with reasonable fidelity. If your installed software does not support RTF, convert to DOCX or PDF first using KaijuConverter; both open in virtually every reader, including free online viewers.

Use EPUB for reading on phones and eReaders since it reflows text to fit any screen. Use PDF for documents with fixed layouts like textbooks with precise formatting, scanned pages, or documents intended for printing.

Upload the RTF to KaijuConverter and pick DOCX, PDF, ODT, RTF, HTML, Markdown, or plain text. Our pipeline runs LibreOffice headlessly plus pandoc for text formats — the same engines behind professional document pipelines. Styles, tables, images, and hyperlinks survive the conversion intact.