G4 to ICO Converter

Quick G4 to ICO conversion — no signup needed

Drop files here. 1 GB maximum file size or Sign Up
to
Facebook Amazon Microsoft Tesla Nestle Walmart L'Oreal

Fax to Digital

Bridge the gap between legacy G4 encoding and ICO — preserve and modernize your fax document archive.

Privacy Guaranteed

G4 uploads are erased upon completion. ICO results are automatically purged from servers within 24 hours.

Simple Workflow

Upload G4, choose ICO, download. Three simple steps — the entire process completes in under a minute.

How to convert G4 to ICO

1

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

2

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

3

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

About formats

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
ICO is the icon file format for Microsoft Windows), introduced with Windows 1.0 in 1985 and serving as the standard container for application icons, file type icons, and shortcut icons throughout the Windows ecosystem. An ICO file bundles multiple image variants within a single container — each at different sizes (16x16, 32x32, 48x48, 256x256, and others) and color depths (4-bit, 8-bit, 24-bit, 32-bit with alpha) — allowing Windows to select the most appropriate image for each display context, from tiny taskbar buttons to large desktop icons. The container structure consists of an ICONDIR header, an array of ICONDIRENTRY records describing each variant, and the image data itself. Since Windows Vista, ICO files support embedded PNG-compressed images for the larger sizes (typically 256x256), dramatically reducing file size while maintaining quality with full alpha transparency. One advantage is automatic size adaptation — Windows pulls the optimal resolution from the ICO container for each context (Explorer list view, desktop tile, Alt-Tab preview), ensuring crisp display without the application managing separate image files. The format's operating system-level integration is another core strength: ICO files serve as the identity mechanism for executables, file associations, and shortcuts across all Windows versions, and web browsers use favicon.ico for website identity in tabs and bookmarks. ICO creation and editing is supported by image editors like GIMP, Inkscape, and dedicated icon tools, and the format remains essential for Windows application development.
Developer: Microsoft
Initial release: 1985

Frequently Asked Questions

Why convert G4 to ICO?

G4 files require specialized fax viewers. Converting to ICO lets anyone open the content easily.

Where can I open ICO files?

Use any web browser, IrfanView, or icon editing tools to view ICO files.

Is fidelity maintained in G4 to ICO conversion?

Yes — the converter reproduces your G4 content in ICO at full fidelity. No visible quality is lost.

Is G4 to ICO free on Convertio?

Yes, basic usage is completely free. Premium plans are available for additional speed and volume.

Can I convert several G4 files simultaneously?

Batch mode is fully supported. Add multiple G4 files and download each converted ICO file individually.

Is my data secure during conversion?

Uploaded G4 files are deleted immediately after conversion. ICO results are automatically removed within 24 hours.