What is inside an ICO file
An ICO file is a container. It holds several images of the same icon in different sizes, so that a program can pick the one that fits, such as 16 pixels for a tab and 256 pixels for a big desktop icon. This tool opens the container and lists what is inside: the size of each image, its color depth, how it is stored and how many bytes it takes.
Save the images
Every image can be saved on its own, and you can take all of them in a ZIP file. Choose the format:
- PNG is the best choice for icons. It keeps transparency. If the ICO stores PNG images, as most modern ICO files do, the original PNG data is copied without any change.
- JPG has no transparency, so transparent parts are filled with the color that you choose.
- WebP keeps transparency and makes small files.
Scale up
Icons are small, and sometimes you need a big picture, for example 512 pixels for a presentation. The Scale box enlarges the images. Smooth scaling blends the pixels, which looks natural for most icons. Sharp pixels keeps every pixel as a hard square, which is better for pixel art and for small icons that you want to see in detail. Enlarging cannot add detail that the icon does not have, so for a sharp big picture you need the original artwork.
Old and new ICO files
The converter reads ICO files with PNG images and the older ones with bitmap images of 1, 4, 8, 24 or 32 bits and a separate transparency mask. A cursor file with the .cur extension has the same structure and can be opened too. If an image inside uses a rare format that cannot be read, it is named in a message, and the others are still saved.
Where ICO files come from
- The favicon.ico of a website. Open the address /favicon.ico in a browser, save it, and drop it here.
- Windows application icons and shortcuts.
- Old icon libraries that you want to use in a new project.
Everything happens in your browser. To make an ICO, use PNG to ICO or JPG to ICO, or the ICO converter, which does both. For a favicon package, see favicon from image.