CUR vs ICO Format Comparison
CUR
Windows Cursor
image/x-win-cursor
VS
Windows Icon File
image/x-icon
ICO
A complete technical comparison of Windows Cursor and Windows Icon File — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
ICO wins on browser support
Feature Support
| Feature | CUR | ICO |
|---|---|---|
| Transparency (Alpha) | Yes | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | Yes |
Windows Cursor
image/x-win-cursor
Extension
.cur
Container
ICO/CUR Container File
Compression
Uncompressed (BMP) / PNG (Supported in newer versions)
Algorithm
None (DIB / BMP)Deflate (If PNG embedded)
Color Depth
1-bit (Monochrome), 4-bit (16 colors), 8-bit (256 colors), 24-bit (True Color), 32-bit (True Color with Alpha)
Developed by
Microsoft Corporation
Released
1985
Magic Bytes
00 00 02 00
Windows Icon File
image/x-icon
Extension
.ico
Container
ICO
Compression
Uncompressed (BMP) / Lossless (PNG)
Algorithm
Uncompressed DIB (Device Independent Bitmap)DEFLATE (via embedded PNG)
Color Depth
1-bit, 4-bit, 8-bit, 24-bit, 32-bit (8-bit Alpha)
Developed by
Microsoft Corporation
Released
1985
Magic Bytes
00 00 01 00
Browser Support Comparison
| Browser | CUR | ICO |
|---|---|---|
Chrome
|
✓ 1
|
✓ All
|
Firefox
|
✓ 1
|
✓ All
|
Safari
|
✓ 1.2
|
✓ All
|
Edge
|
✓ 12
|
✓ All
|
IE (Legacy)
|
✓
|
✓
|
CUR
CUR Strengths
- Natively supported by Windows for desktop cursor customization
- Widely supported by modern web browsers for custom CSS cursors
- Supports an exact hotspot coordinate, which standard image formats like PNG and JPEG lack
Limitations
- Legacy format that is being gradually replaced by SVG and PNG for web implementations
- Does not support animation (animated cursors use the distinct .ani format)
- The MIME type is highly fragmented across systems (e.g., image/cursor, image/x-win-cursor, application/x-cursor)
ICO
ICO Strengths
- Universally recognized as the default fallback for web favicons
- Can store multiple resolutions (e.g., 16x16, 32x32, 256x256) inside a single file
- Supports full 8-bit alpha channel transparency (since Windows XP)
Limitations
- Larger file size compared to equivalent PNGs due to uncompressed BMP usage and multiple resolutions
- Inconsistent MIME type usage across web servers (x-icon vs vnd.microsoft.icon)
- Largely being superseded by SVG and PNG for modern web design
When to choose which format
CUR
Use CUR when…
- Operating System Custom Cursors
- Custom Web Browser Mouse Pointers (via CSS)
- Desktop Application UI
ICO
Use ICO when…
- Website Favicons
- Windows Desktop Icons
- Application Executable Icons
Convert & Edit Online
Free online web tools for CUR and ICO files.
Free Image Resizer
Editor
Resize, scale, crop, and modify dimensions for any photo or graphic.
Use Tool
Image Metadata Remover
Privacy
Clean EXIF, camera, lens, and location tags from your photos.
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WebP to JPG Converter
Universal
Convert modern web images to universal high-compatibility JPG.
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Compress WebP Images
Optimizer
Reduce image file sizes for faster web performance.
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WebP to ICO Converter
Favicon
Generate standard 16x16, 32x32, 48x48 website favicon ICO files.
Use Tool
PNG to WebP Converter
Converter
Convert icon graphics into lightweight WebP format.
Use Tool