Convert JPG to ICO Online

ICO (Windows Icon) files are the standard format for website favicons and Windows application icons. What makes ICO files special is that a single .ico file can contain multiple sizes of the same icon simultaneously - Browsers and operating systems automatically select the most appropriate size for the context (16×16 in browser tabs, 32×32 on the taskbar, 256×256 for folder views on high-DPI displays).

For favicons specifically, modern best practice is to include at least 16×16, 32×32, and 48×48 in the ICO file, plus a separate 180×180 PNG for Apple Touch Icon (used when iOS saves your site to the home screen). The favicon.ico file should be placed in your web root so browsers find it automatically.

Source image quality matters significantly for small icon sizes. Use a square, high-contrast image with a simple subject - Complex photography looks like an indistinct blob at 16×16. Logos with bold outlines and limited colours work best. If your source JPG is 256×256 or larger, the downscaled icon sizes will be crisp.

ICO (Icon) is a Windows container format introduced with Windows 1.0 in 1985. Originally limited to 16-colour 32x32 pixel images, the format evolved through Windows XP (which added 32-bit alpha) and Windows Vista (which embedded PNG inside ICO for 256x256 sizes). A single ICO file contains multiple resolutions so the OS can pick the right one for the Start Menu, taskbar, file explorer or alt-tab switcher. ICO became the de facto favicon standard in 1999 when Internet Explorer 5 introduced favicon.ico, and most browsers still request that path today.

The most common use for converting JPG to ICO is creating a website favicon - The small icon that appears in browser tabs, bookmark lists, and the browser address bar. Every website needs one, and browsers expect it at /favicon.ico on the root domain. An ICO file can bundle multiple sizes (typically 16×16, 32×32, and 48×48 pixels) so the browser picks the most appropriate one for its context.

Windows desktop application developers also use ICO files as application icons. If you are building a desktop app, a custom shortcut, or a Windows installer, ICO is the native format Windows uses for all icon display contexts from the taskbar to the file explorer thumbnail.

Start with the highest-resolution version of your logo or image, as the converter will automatically generate each selected size from the source. A 512×512 or 1024×1024 pixel JPG gives the best results when scaled down to the small sizes that ICO requires.