EPUB to G4 Converter

Convert EPUB pages to Group 4 FAX format online

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Fax-Standard Compression

EPUB pages encoded with Group 4 FAX compression are ready for fax systems, document archives, and enterprise imaging platforms.

Compact Output

G4 compression produces extremely small files from text-heavy EPUB pages — efficient for storage and transmission.

Secure Conversion

Your EPUB is deleted from servers immediately after processing. G4 output files are automatically removed within 24 hours.

How to convert EPUB to G4

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose g4 or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your g4 file right afterwards

About formats

EPUB (Electronic Publication) is an open ebook standard originally developed by the International Digital Publishing Forum (IDPF) and now maintained by the W3C following the organizations' merger in 2017. The first version carrying the EPUB name was approved in October 2007 as a successor to the Open eBook Publication Structure (OEBPS). An EPUB file is essentially a ZIP archive containing XHTML or HTML5 content documents, CSS stylesheets, images, fonts, and metadata organized according to the Open Packaging Format and Open Container Format specifications. The current major version, EPUB 3, supports reflowable and fixed-layout content, embedded multimedia, JavaScript interactivity, MathML equations, and rich accessibility features including semantic markup and media overlays for synchronized text and audio. A defining advantage is universal device support — unlike proprietary formats, EPUB works natively on virtually every non-Kindle e-reader, tablet, and reading application, from Apple Books and Google Play Books to Kobo and dozens of third-party apps. The reflowable text model is another core strength, automatically adapting pagination, font size, and margins to match any screen dimension and user preference. EPUB's open specification and active W3C stewardship ensure long-term preservation and vendor independence, making it the de facto standard for digital publishing across libraries, academic institutions, and commercial retailers worldwide.
Initial release: October 2007
G4 is a monochrome image format based on the ITU-T Group 4 facsimile coding standard (Recommendation T.6), ratified by the CCITT in 1984 as an improvement over Group 3 for use on error-free digital networks like ISDN rather than analog telephone lines. G4 files contain 1-bit image data compressed using exclusively two-dimensional Modified Modified READ (MMR) coding, where each scanline is encoded as a set of differences (changing elements) relative to the line above it. By eliminating the one-dimensional coding fallback and the end-of-line synchronization markers required by Group 3, G4 achieves 20-50% better compression ratios on typical document pages while producing a simpler, more regular bitstream. The format is most commonly encountered as a compression method within TIFF files (TIFF compression tag 4), where it became the standard archival format for scanned documents in enterprise document management, government records, and legal imaging systems. G4 compression is specified at 200, 300, or 400 dpi depending on the scanning application, with 300 dpi being the most common for archival-quality document imaging. One advantage is exceptional compression efficiency for document content: G4's two-dimensional prediction exploits the strong vertical correlation in text and line art pages, typically compressing a 300 dpi letter-size page to 30-50 KB — roughly half the size of equivalent Group 3 encoding. The format's entrenchment in document management infrastructure is another strength — G4 TIFF is the mandated format for many government digital records systems, court filing systems, and corporate archives, supported by every enterprise imaging platform.
Developer: ITU-T (CCITT)
Initial release: 1984

Frequently Asked Questions

Why convert EPUB to G4?

Group 4 FAX compression is the standard for fax transmission and document archiving — ideal for text-heavy EPUB pages going into fax or DMS workflows.

What reads G4 FAX files?

LibTIFF viewers, IrfanView, ImageMagick, Windows Fax Viewer, and most document management systems support Group 4 encoded images.

Is G4 only monochrome?

Yes — G4 is a bi-level compression standard. Color EPUB pages are converted to black and white, which works very well for text.

How compact are G4 files?

Group 4 compression is highly efficient for text and line art — resulting files are typically very small compared to uncompressed bitmaps.

Is EPUB to G4 free?

Yes, free on Convertio. Premium plans add higher file limits and priority processing for business or bulk needs.