ICO Compressor

Compress and optimize ICO icon files to reduce file size. Remove unnecessary icon sizes, reduce color depth, and apply smart compression. Perfect for optimizing favicons and Windows application icons. Create smaller files while preserving quality with our free icon tools.

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ICO Batch Upload
Max 5MB per file - Up to 10 files
Related Icon Tools:
Favicon Generator ICO Analyzer PNG to ICO ICO to PNG Icon Resizer Compress PNG

How to Compress ICO Files

  1. Upload your ICO files by dragging and dropping or clicking the upload area. You can process up to 10 icons at once for batch optimization.
  2. Choose compression level: Select Light for best quality, Balanced for optimal results, or Maximum for smallest file size.
  3. Select icon sizes: Keep only the sizes you need. For favicons, 16px, 32px, and 48px are typically sufficient. Use our Favicon Checker to verify compatibility.
  4. Adjust color depth: 32-bit preserves transparency, 8-bit offers maximum compression. Consider your color palette needs.
  5. Download optimized icons: Get individual files or download all as a ZIP archive.
Pro tip: If you need to create new icons, use our PNG to ICO converter which automatically optimizes during conversion. For existing icons, check their structure first with the ICO Analyzer.

Compression Modes Explained

Light

Best for high-quality application icons. Minimal compression that preserves all visual details. Reduces file size by 10-30% by optimizing internal structure without affecting image quality. Ideal for Windows application icons where quality matters.

Balanced

Recommended for most use cases. Smart compression that finds the optimal balance between file size and quality. Typically reduces size by 30-50%. Perfect for favicons and web icons where both size and appearance matter.

Maximum

Best for smallest possible file size. Aggressive compression that prioritizes file size over quality. Can reduce size by 50-70%. Best for simple icons, low-bandwidth situations, or when icon detail is less critical.

Icon Size Guide

16px

Browser tab favicons, small toolbar icons. Essential for any favicon.

32px

Windows taskbar, high-DPI browser tabs. Standard favicon size for most browsers.

48px

Windows desktop shortcuts, medium icons. Recommended for Windows applications.

64px

Large Windows icons, high-resolution displays. Optional for most use cases.

128px

Extra large icons, Windows Vista+ large view. Useful for app icons.

256px

Windows Vista+ jumbo icons, high-DPI displays. Largest standard ICO size.

Frequently Asked Questions

ICO files can contain multiple images at different sizes and color depths. Our compressor optimizes each embedded image, removes unused sizes, reduces color depth where appropriate, and uses PNG compression for larger sizes (256px+). This can significantly reduce file size without visible quality loss. For more details about ICO structure, use our ICO Analyzer.

With Light and Balanced modes, quality loss is minimal or imperceptible. Maximum mode may show slight quality reduction, especially with gradients or complex images. For favicons displayed at small sizes, even Maximum compression usually looks fine. Preview your results before downloading, or compare with the ICO to PNG converter.

For web favicons, 16px, 32px, and 48px cover most use cases. 16px is for standard browser tabs, 32px for high-DPI displays and bookmarks, and 48px for Windows shortcuts. You can remove larger sizes (64px, 128px, 256px) unless needed for Windows applications. Use our Favicon Checker to test compatibility.

ICO files can store images as either BMP or PNG format internally. PNG compression is more efficient for larger sizes (256px+), significantly reducing file size. Enabling this option converts larger embedded images to PNG format while keeping smaller sizes as BMP for maximum compatibility. Learn more about PNG compression.

32-bit is best for icons with transparency, gradients, or many colors. 8-bit (256 colors) works well for simple icons with flat colors and offers the smallest file size. If your icon has transparency, 32-bit is recommended. Use our Color Picker to check how many colors your icon uses.

Results vary based on the original file and settings. Removing unused sizes alone can reduce file size by 50% or more. Combined with color depth reduction and PNG compression, you can often achieve 60-80% reduction. Heavily optimized icons may see less improvement. For comparison, try our PNG Compressor on extracted images.