# JPG to ICO Converter: Create Favicons and Windows Icons from Your Photos
The ICO format is Microsoft's standard for Windows application icons and website favicons. Unlike simply renaming a JPG as .ico, a genuine ICO file requires a specific binary structure with 22-byte headers and an embedded image directory. JPG is the most common starting point for creating these icons — a company logo, a profile photo, or any image you want to turn into the visual icon of your application or website.# JPG or ICO? When to use each format
JPG is a source format, not a destination for icons. Perfect for photographs and banners, but incompatible with systems that require icons: Windows Explorer, the browser's bookmark bar, desktop shortcuts, or PWA application manifests. An operating system or browser looking for an icon expects the ICO format — and if it doesn't find it, it will display a generic icon or a broken square.The ICO format was designed to contain multiple resolutions in a single file: 16×16 for the bookmark bar, 32×32 for shortcuts, 48×48 for the file explorer, and 256×256 for high-density displays. Browsers and operating systems automatically select the appropriate resolution based on the display context — the user doesn't have to manage anything.# Comparison: Local vs Cloud Conversion
Cloud Converters
Tools that upload your files to a remote server.
- Network latency on upload and download
- Your corporate logos stored on third-party servers
- File size limits and daily conversion caps
- Intrusive ads and third-party trackers
Our Local Architecture
Direct processing on your hardware using Vanilla JS technology.
- Instant speed — zero network latency
- Complete privacy — 0 bytes sent externally
- No MB limits or file count restrictions
- Clean interface, no ads or tracking
# How it works technically
The JPG is decoded and drawn onto an in-memory HTML5 Canvas. Since the ICO format requires a square image, the engine automatically detects if the JPG is rectangular and crops it by centering the most relevant part. It then builds the standard Microsoft ICO header with the correct magic number (00 00 01 00), the image directory, and the encoded pixel data. The result is a genuine binary .ico file — not a renamed PNG.Since JPG lacks an alpha channel, the resulting ICO will also have no transparency — it will have a solid background inherited from the original photograph. If you need a favicon with a transparent background (for example, to adapt to dark or light bookmark bars), the recommended workflow is: remove the background in an editor, save as PNG, and use the PNG to ICO converter.Tip: multiple resolutions in a single ICO
ICO files can pack multiple resolutions into a single file — the browser or OS automatically picks the most appropriate one for each context. For the best possible result, use a square JPG of at least 256×256 pixels as your source: this gives the converter enough information to generate sharp 16×16, 32×32, and 48×48 sizes without pixelation.# Use cases and compatibility
- Website favicon: compatible with all browsers including Internet Explorer.
- Folder and desktop icon customization in Windows 10/11.
- Shortcut icon for desktop applications or installers.
- Application icon for Electron projects or PWA applications.
- Icons for file management systems and corporate file explorers.