What an ICO file is
ICO is the icon format used by Windows for application and shortcut icons, and it is also the traditional format for website favicons, the small image shown in a browser tab. An ICO file is really a container: a small header, a directory of entries, and then the image data for each entry. A single file can hold several sizes of the same icon so the system can pick the best one.
Inside the container, modern ICO files can store each image as PNG data. That is what this tool does. It draws your image at the size you pick, encodes it as PNG, and wraps it in a valid ICO header and directory entry. The result is one icon at one size.
Because the icon is tiny when displayed, simple artwork with strong shapes and good contrast reads far better than a detailed photograph.
When you need an ICO file
The most common reason is a favicon. Many sites still serve a file named favicon.ico from the root of the domain, and some older browsers and tools look for that file specifically. Having your logo in ICO form is a quick way to satisfy that.
You may also need one for a Windows desktop app, an installer, or a custom folder or shortcut icon. These tools usually refuse PNG or JPG files and want an .ico.
If your source is a different format, you do not have to convert it first. Any image your browser can open is accepted. If the logo is oversized or oddly shaped, trimming it first with the Image Resizer gives you better control over what ends up in the icon.
How to turn an image into an ICO
- Drop an image onto the upload area or click it to choose one. Any common image format your browser supports will work.
- A preview of your image appears. Use the Icon size menu to pick one of 16, 32, 48, 64, 128 or 256 pixels. The default is 256 by 256.
- Click Convert to ICO. The conversion is done in your browser, so the image is not uploaded.
- Click Download to save the result. The file is always named favicon.ico.
- To try a different image or size, click Start over and begin again.
For a typical favicon, 32 is a common choice, while 256 suits desktop icon use. Because each conversion produces a single size, run the tool again if you need more than one.
Things to know before you use the result
The tool draws your image into a square canvas of the chosen size. It does not keep the original proportions, so a wide or tall picture will be stretched to fit. Crop your image to a square beforehand for the cleanest result.
The ICO contains only the one size you selected. It is not a multi-resolution icon bundle. Windows and browsers will scale it as needed, but a hand-tuned set of sizes will look sharper at very small dimensions.
Transparency from a PNG source is preserved because the icon stores PNG data. A JPG has no transparency, so it will appear as a solid square.
Finally, the download name is fixed. If you are producing several icons, rename each file after saving so they do not overwrite one another.