WOFF to G4 Converter

Render web fonts as Group 4 fax-compressed images online

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Document Standard

G4 compression is the backbone of document imaging — render WOFF fonts into the format used by scanners and archival systems worldwide.

Excellent Compression

Group 4 achieves outstanding compression ratios for monochrome text images — small files from WOFF glyph renders without any quality loss.

Online Processing

No scanner drivers or document software needed. Convertio handles the WOFF to G4 conversion entirely through your web browser.

How to convert WOFF 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

WOFF (Web Open Font Format) is a web font container format developed by Jonathan Kew, Tal Leming, and Erik van Blokland, and standardized by the W3C as a Recommendation in December 2012. The format wraps existing TrueType or OpenType font data in a compressed container with additional metadata, specifically designed for efficient delivery over HTTP as part of web pages using the CSS @font-face rule. WOFF applies table-level zlib compression to the font data, typically achieving 40-50% size reduction compared to raw TTF or OTF files, while preserving every table and glyph exactly. An extended metadata block allows foundries to embed licensing information, credits, and descriptions that travel with the font file. WOFF was created to address a practical impasse: type foundries were reluctant to allow their fonts on the web in raw TTF/OTF form (easily installable as desktop fonts), while the web standards community needed a freely implementable font delivery mechanism. One advantage is universal browser support — every modern browser across desktop and mobile platforms renders WOFF natively, making it the baseline format for web typography. The distinct file signature and container structure also provides a licensing benefit, giving foundries a format distinguishable from desktop fonts while remaining technically straightforward. WOFF 2.0, standardized in March 2018, replaces zlib with Brotli compression for an additional 20-30% size reduction and has achieved similarly broad browser adoption. Together, WOFF and WOFF2 enabled the custom web typography revolution that transformed web design from a handful of system fonts to millions of typeface options.
Developer: W3C
Initial release: December 13, 2012
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 WOFF to G4?

Group 4 compression is the standard for document scanning and archival. Font renders in G4 achieve excellent compression for monochrome text images.

How do I open a G4 file?

TIFF viewers, ImageMagick, and document management systems handle G4-compressed images. Scanning software and multifunction printers support G4 natively.

How does G4 differ from G3?

G4 offers better compression than G3 by using two-dimensional coding. G4 was designed for higher-quality connections where error correction is reliable.

Is G4 lossless?

Yes, Group 4 is a lossless compression scheme. Every pixel of the rendered font glyph is preserved exactly — no quality degradation occurs.

Is WOFF to G4 conversion free?

Yes, fully free on Convertio — run the conversion online without document imaging software or fax tools on your computer.