PNG to ICO – Favicon or Windows App Icon

The .ico format is one file that holds several pre-rendered icon sizes inside it. Browsers and Windows pick the size they need at runtime. Which sizes you actually want depends on where the .ico is going to be used, so DropFormat has split PNG-to-ICO into two pages with different defaults.

Website favicon (most common)

If you need a favicon.ico for browser tabs, bookmarks, and the address bar, you want the small set: 16×16, 32×32, and 48×48. Total file size is under 10 KB. The converter below produces that bundle.

The conversion runs entirely in your browser. The file never leaves your computer.

For more detail on favicon-specific guidance (source PNG requirements, when to use ICO instead of a PNG favicon, transparency notes), see the dedicated favicon from PNG page.

Windows app or desktop shortcut icon

If you are building a Windows installer (Inno Setup, NSIS, WiX), embedding an icon in a .exe, or making a custom desktop shortcut, you want the full Windows ladder: 16, 24, 32, 48, 64, 128, and 256. The 256 size is what Vista and later use for the Explorer thumbnail view. The smaller sizes cover title bars, taskbar, and high-DPI scaling points.

The resulting .ico is around 100-150 KB. A favicon-sized .ico in those contexts produces fuzzy icons in the Explorer thumbnail grid because Windows has to upscale the largest embedded image.

Go to PNG to Windows app icon for the full-ladder converter.

How to choose

If the .ico is going on a website (referenced by <link rel="icon"> or named favicon.ico at the site root), use the favicon converter above. Small file, exactly the right sizes.

If the .ico is going inside a Windows executable, installer, or desktop shortcut, use the app icon page. Bigger file, but those contexts render at sizes the favicon set cannot cover.

If you only know that something asked you for “a .ico file” without context, the favicon set above is the safer default. Web contexts vastly outnumber installer contexts, and a small file embedded in the wrong place is harmless. A 150 KB favicon, on the other hand, is a permanent tax on every visitor’s page load.

What is the ICO format?

ICO is a Windows container that packs multiple icon images into one file. Each embedded image has its own pixel dimensions and color depth, and whoever displays the icon picks the entry that matches the size they need to render. Browsers and the Windows shell both work this way, but they ask for different size sets, which is why the same input file is wrong for both use cases without picking a preset first.

The format was introduced with Windows 1.0 and has been extended since. Modern .ico files use PNG-compressed entries for the larger sizes, which is what keeps a full 256-pixel ladder under 200 KB. The DropFormat encoder always writes PNG-compressed entries.

Need to extract a PNG from an existing .ico? Use ICO to PNG. Have a JPG source? Use JPG to ICO.