Image format

ICO

An icon resource containing several raster sizes and colour depths, with masks or alpha for transparency.

Convert ICO to

Choose a target format for your ICO images.

JPEGJPEGICO → JPEG PNGPNGICO → PNG WebPWebPICO → WebP AVIFAVIFICO → AVIF HEICHEICICO → HEIC HEIFHEIFICO → HEIF

All 21 conversions

GIFGIFICO → GIFWith caveat TIFFTIFFICO → TIFF BMPBMPICO → BMP JPEG XLJPEG XLICO → JPEG XL JPEG 2000JPEG 2000ICO → JPEG 2000 QOIQOIICO → QOI TGATGAICO → TGA PCXPCXICO → PCX PPMPPMICO → PPM PGMPGMICO → PGMWith caveat PBMPBMICO → PBMWith caveat PAMPAMICO → PAM HDRHDRICO → HDR EXREXRICO → EXR PDFPDFICO → PDF

Marked paths may need steps such as flattening, rasterization, tone mapping or animation loss.

Convert to ICO

Choose a source format to convert to ICO.

JPEGJPEGJPEG → ICO PNGPNGPNG → ICO WebPWebPWebP → ICO AVIFAVIFAVIF → ICO HEICHEICHEIC → ICO HEIFHEIFHEIF → ICO

All 36 conversions

GIFGIFGIF → ICOWith caveat TIFFTIFFTIFF → ICO BMPBMPBMP → ICO SVGSVGSVG → ICO JPEG XLJPEG XLJPEG XL → ICO JPEG 2000JPEG 2000JPEG 2000 → ICO QOIQOIQOI → ICO TGATGATGA → ICO PCXPCXPCX → ICO PPMPPMPPM → ICO PGMPGMPGM → ICO PBMPBMPBM → ICO PAMPAMPAM → ICO HDRHDRHDR → ICOWith caveat EXREXREXR → ICOWith caveat PSDPSDPSD → ICOWith caveat PDFPDFPDF → ICOWith caveat DNGDNGDNG → ICO Canon CR2Canon CR2Canon CR2 → ICO Canon CR3Canon CR3Canon CR3 → ICO Canon CRWCanon CRWCanon CRW → ICO Nikon NEFNikon NEFNikon NEF → ICO Sony ARWSony ARWSony ARW → ICO Fujifilm RAFFujifilm RAFFujifilm RAF → ICO Olympus ORFOlympus ORFOlympus ORF → ICO Panasonic RW2Panasonic RW2Panasonic RW2 → ICO Pentax PEFPentax PEFPentax PEF → ICO Sigma X3FSigma X3FSigma X3F → ICO Kodak RAWKodak RAWKodak RAW → ICO Hasselblad 3FRHasselblad 3FRHasselblad 3FR → ICO

Marked paths may need steps such as flattening, rasterization, tone mapping or animation loss.

About ICO

Windows Icon

ICO packages raster images for icons rather than a single photographic canvas. One file can contain several sizes and colour depths, allowing a receiving system to select an appropriate image for its display context. The contained pictures have fixed pixel dimensions, even when the icon resource offers several alternatives.

Windows icon workflows use colour data with transparency masks or 32-bit alpha. Modern icon resources can use compressed image payloads, so ICO is a container rather than one compression algorithm. Legacy readers and authoring tools may accept only particular depths or layouts; image count does not represent an animation timeline.

Use ICO for Windows application icons and favicon workflows that explicitly request an ICO resource. Design small sizes deliberately instead of assuming that one large image will downscale cleanly. Exporting to a normal image format usually selects one embedded size; it does not preserve the full icon collection.

Key capabilities

Compression: Depends on variant
Transparency: Yes
Animation: No
Extensions: .ico
MIME type: image/vnd.microsoft.icon, image/x-icon · x-icon is an unregistered alias
Metadata: Image dimensions, Colour depth
Best for: Application icons & favicons
Multiple images: Alternative icon sizes

ICO compression depends on the embedded image payload. Multiple sizes are alternatives, not animation frames; transparency handling differs between old masks and alpha-capable images.

History of ICO

ICO belongs to Windows resource conventions. Its evolution reflects changing display sizes and colour capabilities rather than a photographic coding standard.

Windows resources
Reusable icon resources
Microsoft defines ICON resources that refer to icon files. The resource model explicitly permits more than one image in an icon or cursor resource.
Colour displays
Several colour depths
Microsoft’s icon guidance includes 4-bit, 8-bit and 24-bit-plus-alpha variants. Keeping alternatives addresses different display and resource contexts.
Windows Vista
Larger alpha icons
The Windows icon guidance documents larger sizes and warns that older Visual Studio tooling does not support Vista icon features. Authoring-tool support can lag behind the icon format used by the system.

ICO compared

Different formats, different trade-offs. Choose for the image and the workflow.

PNG

ICO vs PNG

PNG preserves decoded pixels losslessly and can carry alpha. It is useful for transparent graphics and screenshots; it does not preserve editable document layers or camera sensor data, and photographic files can be large.

SVG

ICO vs SVG

SVG keeps shapes and text as vector descriptions, which remain sharp when resized. It suits diagrams and symbols; converting a photo into an SVG wrapper does not reconstruct editable vector shapes.

BMP

ICO vs BMP

BMP suits Windows bitmap interchange and simple pixel inspection. Uncompressed variants are easy to decode but can be large; palette, alpha and colour-profile behaviour depend on the header version.

WebP

ICO vs WebP

WebP combines lossy or lossless 8-bit image coding with alpha and animation. It is a web delivery option when those features matter; high-precision samples and editable source structures need another working format.

ICO FAQ

What does this format store?

How does compression affect quality?

ICO compression depends on the embedded image payload. Multiple sizes are alternatives, not animation frames; transparency handling differs between old masks and alpha-capable images.

Why does one ICO contain several images?

The system can choose a size and colour depth appropriate to the icon context. These entries are alternative representations; ICO itself does not assign animation timing.

What should I check before opening the file?

Check the embedded image sizes, encoding and alpha support in the target system. Renaming PNG to ICO does not create a multi-image icon directory.

What changes when I export to another format?

Extracting to PNG selects an embedded image and can preserve its decoded alpha. Creating ICO requires selecting dimensions and payload variants; enlargement of a small icon cannot restore absent detail.

When is this format useful?

Sources

ICO