ICO to RB Converter

Switch from ICO to RB format online for free

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Full Resolution

Convertio extracts the highest resolution image from your ICO container and converts it to RB — preserving maximum detail.

Batch Support

Queue multiple ICO files and convert them all to RB at once — saving time when you have many files to process in a single session.

Data Safety First

Convertio deletes your ICO uploads instantly after processing and removes RB output within 24 hours — no files linger on servers.

How to convert ICO to RB

1

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

2

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

3

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

About formats

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
RB is the native ebook format of the Rocket eBook, one of the first commercially available dedicated e-reading devices, developed by NuvoMedia and released in October 1998. Founded by Martin Eberhard and Marc Tarpenning — who later co-founded Tesla Motors — NuvoMedia designed the Rocket eBook as a handheld device with a reflective LCD screen, capable of storing approximately ten books in its internal memory. The RB format packages HTML-based content along with embedded images, metadata, and a table of contents into a single binary container optimized for the device's limited hardware. Content was purchased and downloaded through NuvoMedia's RocketLibrarian desktop software. A notable advantage of the format was its early support for bookmarking, annotation, dictionary lookups, and adjustable font sizing — features now standard on modern e-readers but revolutionary in the late 1990s. The Rocket eBook demonstrated viable commercial demand for dedicated reading devices, paving the way for subsequent platforms from Sony, Amazon, and others. NuvoMedia was acquired by Gemstar-TV Guide International in 2000, which discontinued the device line in 2003. While RB files are largely a historical curiosity today, they can be converted to modern formats using ebook management tools, and the format remains significant as a pioneering chapter in the evolution of digital reading.
Developer: NuvoMedia
Initial release: 1998

Frequently Asked Questions

Why convert ICO to RB?

Rocket eBook format wraps your icon for legacy reading hardware — a niche conversion for distributing content on early e-reader devices.

What programs open RB files?

Common options include Calibre, legacy Rocket eBook devices. The format has good support across major operating systems.

Which icon size gets used from my ICO?

Convertio extracts the highest resolution image stored in your ICO file for conversion to RB — giving you the best quality available in the icon.

Are my files safe during conversion?

Convertio uses encrypted connections for all transfers. Your ICO uploads are deleted immediately after conversion, and RB downloads are removed within 24 hours.

Is the conversion process fast?

ICO to RB conversion usually finishes in a few seconds. Larger files may take slightly longer, but the cloud-based processing keeps things efficient.

Is batch ICO to RB conversion available?

Absolutely — upload multiple ICO files simultaneously and convert them all to RB at once. Batch mode saves considerable time on repetitive conversions.

ICO to RB Quality Rating

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