ICO format is used in Windows for system icons. The designation ICO is short for Icon.
Windows has a built-in library of icons. However, developers of programs and websites usually use their own images for the icons of their products. The icon, as a rule, contains the logo of the application or developer, or some expressive picture, from which you can understand the essence of the program.
The ICO format includes more than one icon file, and a whole set. The fact is that different sizes of the icon are shown in different views. Reduced automatically large version may be illegible, and enlarged small - blurred. Therefore ICO is a file that includes several icon sizes.
Even if you place an icon on the desktop, at the same monitor resolution, the same icons may seem very large or unacceptably small. When choosing the optimal image style, Windows selects appropriate icons from the library.
The standard icon has a "square" aspect ratio. The ICO file assumes the following dimensions: 16x16, 32x32 and 48x48 pixels. There are also less common options, with a side from 24 to 128 pixels. Theoretically, the maximum allowable value of the side of the square is 256 pixels, but in practice such icons are rarely used. Some file managers are able to scale icons (for example, Total Commander).
The user of the computer is usually satisfied with the standard icons that are supplied with each program. But you can decorate your computer and make it easier to find the right files and folders if you change them with different icons. Often, file managers have their own set of standard icons, but you can also create your own.
There is a kind of ICO file, like Favicon. It is displayed in the browser as an "icon" of the website. For favicon, the standard minimum size is 16x16 pixels. For more information about the icon for the site, see the article "Site icon".
Conversion
Free online converter will help you create multivariate icons based on your graphic files. Make sure that your original file maintains a "square" aspect ratio. If not, it can be trimmed to the desired standard, the image size in this case does not necessarily have to match the size of the desired icon. Online converter itself will change the size to the specified settings.
The source file can have almost any format (list of supported formats). We recommend that you take care that the source file is as high as possible. These can be PSD, TIFF and other files. If your icon is the result of design efforts in a professional graphics editor, we recommend using the file of the native format of the editor as the source file.
Our converter offers to automatically generate the most popular size options for the icon. When converting a file to ICO format, you can choose not only the icon sizes represented in the final file, but also the color depth. For icons of 256x256 pixels size it can be 32 bits, for smaller icons it will automatically be 8 bits.
The size of the resulting ICO file will be slightly larger than the total size of the incoming files. The reason for this is that all the files of individual icons are stored in an uncompressed ICO file.