ICO converter

ICO is an icon container, not just a tiny bitmap. A file starts with an icon directory that lists one or more images by width, height, color count, bit depth, byte size, and offset. The image payloads may be older DIB-style bitmaps with AND masks, or PNG-encoded images in newer icon files. This lets one .ico carry 16, 32, 48, 64, 128, or 256 pixel variants so Windows shells, browsers, and shortcuts can choose an appropriate size. Our image routes can create ICO from PNG, JPG, SVG, BMP, WebP, AVIF, GIF, HEIC, PSD, or TIFF, and convert ICO back to common image formats or PDF.

The format's history explains most mistakes. Legacy Windows icons used palette or bitmap images plus a one-bit transparency mask. Modern icons can use 32-bit alpha and PNG compression, but older consumers may only read some entries. A 256 by 256 icon can look sharp in a desktop settings page while a 16 by 16 tab icon becomes unreadable. The container may hold several variants, and a converter or viewer might pick only the first image. Color depth and alpha handling differ across old applications, especially when an icon is created from a photo or detailed logo rather than a purpose-drawn symbol.

Readers and writers include browsers loading favicons, Windows Explorer, Electron apps, desktop shortcut builders, installers, icon editors, CMS tools, and build scripts for web apps. Modern websites often use SVG or PNG icons alongside an ICO fallback because different devices request different assets. Native Windows applications still expect .ico in resource files. The best source is usually a vector logo or carefully drawn PNG layers, not a random screenshot. Creating an ICO is a design export step as much as a file conversion, because recognizability at tiny sizes must be verified.

ICO conversion gotchas center on picking the right subimage. ICO to PNG is useful for extracting a visible icon, but check which size was chosen. ICO to JPG removes transparency and is rarely appropriate except for preview thumbnails. PNG or SVG to ICO should generate the sizes your target needs and preserve alpha. ICO to PDF only embeds a selected raster icon on a page. Before conversion, decide whether you need a favicon fallback, a Windows app resource, or a preview image. Then inspect small sizes, alpha edges, and dark-mode contrast before shipping the icon set.