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ICO files: what they are and how to make a favicon or Windows icon

ICO is the Windows icon container: one file holding the same picture at several sizes (16, 32, 48, 256 pixels and so on) so the system can pick the right one. It is still what browsers look for as favicon.ico and what Windows uses for program and folder icons.

What is an ICO file?

ICO is the Windows icon format, dating back to Windows 1.0. Unlike a normal image it is a container: one file holds the same picture at several sizes and color depths, so Windows can pick the 16-pixel version for a list view and the 256-pixel version for the desktop. Browsers adopted the same format for favicon.ico, the little image in the tab and bookmarks bar.

Which sizes does a favicon need?

16 × 16 for the tab and address bar, 32 × 32 for high-density screens and taskbar pins, and 48 × 48 for Windows shortcuts. Adding 256 × 256 covers app-style icons. Modern ICO files store each size as a PNG, which keeps transparency and file sizes small, and every browser and Windows since Vista accept that.

Making and unpacking icons

Start with a square PNG at least 256 pixels wide, ideally simple and bold since it must read at 16 pixels. The PNG to ICO tool scales it to each size you tick and bundles them. Going the other way, the ICO to PNG tool pulls out the largest image inside so you can edit it.

Frequently asked questions

Can I use a PNG as a favicon instead of ICO?

Modern browsers accept PNG and SVG favicons via a link tag. ICO remains the fallback that everything, including old browsers and Windows, understands.

Why does my icon look blurry at small sizes?

Because a detailed image was shrunk to 16 pixels. Design a simplified version for the small sizes, or start from a bold, high-contrast shape.

Convert or edit ICO files

Resize to 8×8Resize any image to exactly 8×8 pixels in your browser, with smooth or crisp pixel-art scaling and transparent paddingResize to 16×16Resize any image to exactly 16×16 pixels in your browser, with smooth or crisp pixel-art scaling and transparent paddingResize to 32×32Resize any image to exactly 32×32 pixels in your browser, with smooth or crisp pixel-art scaling and transparent paddingResize to 64×64Resize any image to exactly 64×64 pixels in your browser, with smooth or crisp pixel-art scaling and transparent paddingResize to 128×128Resize any image to exactly 128×128 pixels in your browser, with smooth or crisp pixel-art scaling and transparent paddingResize to 256×256Resize any image to exactly 256×256 pixels in your browser, with smooth or crisp pixel-art scaling and transparent paddingCrop ImageCrop photos to a square, 16:9, 9:16, 4:5, or exact pixel size in your browserRotate ImageRotate images by 90, 180, or 270 degrees and flip them horizontally or vertically in your browserICO to PNG.ico → .pngPixel Art UpscalerScale pixel art, sprites, and game textures up 2x to 16x with crisp nearest-neighbour scaling, in your browser

Make ICO files

PNG to ICOConvert a PNG into a multi-size ICO file for favicons and Windows icons, in your browserJPG to ICOTurn a JPG photo or logo into a multi-size ICO icon file in your browser