Why convert an icon to PNG
ICO is a special format used for Windows program and folder icons and for website favicons, the little picture shown in a browser tab. It works well for that job, but almost nothing else opens it comfortably: image editors may refuse it, design tools don't accept it as an upload, and you can't drop it into a document, a slide or a chat as a normal picture.
Converting the ICO to PNG gives you an ordinary image file. Web designers do this when they only have a site's favicon and need the logo for a mockup. Developers do it to check what an icon actually looks like. Anyone who downloaded an icon pack in ICO format can use this to get versions that work in Canva, PowerPoint, Google Docs or a photo editor.
Transparency and size
Icons usually have a transparent background so they sit nicely on any color. PNG supports transparency, so the transparent areas stay transparent in the converted image.
Icon files are small by nature. Favicons are often designed at 16, 32 or 48 pixels, and even desktop icons rarely go beyond 256 pixels. The PNG you get is the image your browser reads from the ICO file, so it can't be larger or more detailed than what the icon contains. If you enlarge a tiny favicon afterward, it will look blocky; for a sharp large logo, try to get the original artwork.
What you can do next
Once the icon is a PNG, you can keep working without selecting it again. “Resize image” changes its dimensions in pixels. “PNG to SVG” can trace a simple icon with few colors into real vector shapes, which then scale cleanly to any size. And if you edited the PNG and want an icon again, “PNG to ICO” builds a new .ico with several sizes inside.
You can also use the PNG directly as an app icon in tools that require PNG, as a social media avatar for a project, or in documentation where you want to show a program's icon.
In your browser, for free
ConvertirDocs converts the ICO on your device. The file is never uploaded or stored on a server, there's no sign-up and no limit on how many icons you convert. Select a whole set of icons and download every PNG together in a ZIP.