ICO File Format: Everything You Need to Know

ICO is the image format used for website favicons and Windows application icons. Despite its age, ICO remains essential for web development and Windows software. Here's everything you need to know about working with ICO files.

What is ICO?

ICO (Icon) is a file format that can contain multiple image sizes in a single file. A typical ICO file might include 16x16, 32x32, 48x48, and 256x256 pixel versions of the same icon, allowing the operating system or browser to use the most appropriate size.

ICO for Favicons

The favicon (favorite icon) is the small icon displayed in browser tabs, bookmarks, and history. While modern browsers support PNG and SVG favicons, ICO remains the most universally compatible format. For maximum compatibility, include a 32x32 ICO favicon at /favicon.ico in your site's root.

Recommended Sizes

• 16x16 — browser tabs, address bar
• 32x32 — Windows taskbar, bookmark bars
• 48x48 — Windows desktop icons
• 64x64 — high-DPI browser tabs
• 128x128 — Chrome Web Store
• 256x256 — Windows Vista+ large icons

Creating ICO Files

The easiest way to create an ICO file is to convert from PNG. Design your icon at the largest size needed (typically 256x256 or 512x512) as a PNG, then convert PNG to ICO. Our converter creates properly formatted ICO files suitable for both web and desktop use.

Modern Favicon Setup

For modern websites, the recommended favicon setup includes both ICO and PNG:

• favicon.ico — 32x32 ICO file in site root (legacy support)
• icon.png — 192x192 and 512x512 PNG icons (modern browsers and PWAs)
• apple-touch-icon.png — 180x180 PNG for iOS home screen

Converting ICO Files

Need to extract an icon from an ICO file for editing? Convert ICO to PNG for universal compatibility with image editors.