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ICO

ICO — Windows Icon File

Image

ICO files bundle multiple image sizes for Windows icons and browser favicons. Compressing an ICO reduces the size of each embedded image layer using lossless optimization, cutting the overall file size by 20–50% without affecting the crisp appearance of icons at any size.

up to 50%Powered by Pillow.ico

✓Common use cases

  • ›Optimizing browser favicons for faster initial page load
  • ›Reducing ICO size for desktop application installers
  • ›Compressing multi-resolution icon bundles for Windows apps
  • ›Shrinking taskbar icons without losing sharpness at 16×16 or 256×256

★Advantages

  • ›Reduces favicon download time on every page view
  • ›Lossless optimization — icons remain perfectly sharp at all sizes
  • ›Handles multi-resolution bundles in a single compressed file
  • ›Compatible with all Windows versions and major browsers

⚙Technical details

ICO is a container that embeds one or more BMP or PNG frames at different resolutions (16×16, 32×32, 48×48, 256×256). Modern ICO files use PNG compression for large frames and BMP with RLE for smaller ones. Optimization targets each embedded frame independently.

Compress your ICO file

Drop your ICO file here

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.ico

Max file size: 100 MB · Your file is processed securely and deleted after compression.

Frequently asked questions

Does compressing ICO reduce quality?

For image compression, quality depends on the setting you choose. At 75–85% quality the difference is barely perceptible. For lossless formats like PNG, compression is entirely lossless — no pixel data is discarded.

How much can I reduce a ICO file?

ICO files can typically be reduced by up to 50% depending on the source content and the compression level you select. Files with lots of detail compress less than simpler content.

Is my ICO file safe when I compress it?

Yes. Your file is uploaded over an encrypted HTTPS connection, processed on our secure servers, and permanently deleted immediately after you download the compressed output. We never store or share your files.

What tool is used to compress ICO files?

We use Pillow — a battle-tested, open-source compression engine trusted by developers worldwide — to process ICO files reliably and efficiently.