Convert PNG to ICO
A real .ico is not one image — it is several, bundled together, so Windows and browsers can each take the size they need. This builds all of them from one PNG.
Tap to toggle. All selected sizes go into one file — Windows and browsers pick whichever they need.
An .ico file holds more than one icon
This is the part most converters skip. The ICO format is a container: it carries a directory listing several images at different pixel sizes, and whatever is displaying the icon picks the closest match. Windows Explorer reaches for 16 px in a list view, 48 px on the desktop and 256 px in the large-icon view. A browser tab wants 16 or 32. A pinned Windows tile wants 256.
Rename a PNG to .ico and none of that exists — you have one image at one size, scaled badly for every context that is not it. Renaming also produces a file that is not an ICO at all, which some software rejects outright. Building a real container takes a fraction of a second and this page does it properly.
Which sizes to tick
For a website favicon, 16 · 32 · 48 is the practical set, with 256 added if you want Windows to have something decent when the file gets pinned or shown large. That is the default selection. Adding every available size costs you file weight for cases nobody will hit — a full six-size icon typically lands between 20 and 60 KB, against roughly 5–15 KB for the default three-plus-one.
Each size is drawn separately from the source image rather than by scaling a scaled copy, so the small versions are as sharp as the source allows. What no tool can do is invent detail: a logo with hairline strokes and small lettering will be unreadable at 16 px no matter how it is produced. If the icon matters, draw a simplified 16 px version by hand and build two files.
Squares, and what happens if yours is not one
Icons are square. A non-square image is fitted inside the square with its aspect ratio intact and transparent space around it, rather than being stretched or cropped — a squashed logo is worse than a letterboxed one. If you would rather it filled the frame, crop the PNG to a square before converting.
Where the file goes
For a website, put favicon.ico in the root directory. Browsers request /favicon.ico automatically even with no markup, which is precisely why the ICO format is still around three decades on. Modern browsers will also honour an explicit tag, and it is worth adding both:
<link rel="icon" href="/favicon.ico" sizes="any">
Windows shortcuts and executables take an .ico too — right-click the shortcut, Properties, Change Icon, and point it at the file. If your source artwork is a vector rather than a PNG, run it through SVG to PNG at 256 px first and bring the result back here.
Common questions
Why not just rename my PNG to .ico?
Because the extension does not change the contents. Software that actually parses the file will find PNG data where an ICO directory should be, and you lose the whole point of the format — several sizes in one file, each rendered for its own context.
Which sizes do I actually need?
16, 32 and 48 cover browser tabs and Windows Explorer. Add 256 if the icon will ever be shown large or pinned. Those four are selected by default; 64 and 128 are available but rarely requested by anything.
Is transparency kept?
Yes. Each size is stored as PNG data inside the container, which supports a full alpha channel. Tick the flatten option only if you specifically need a white background.
What if my image is not square?
It is centred inside a square canvas with transparent padding, preserving the aspect ratio. Nothing is stretched or cut off. Crop to a square first if you want it to fill the icon edge to edge.
Can I use a JPG or an SVG as the source?
A JPG works — drop it in and it is treated the same way, though it has no transparency to keep. An SVG needs rasterising first; convert it to a 256 px PNG and use that.
Will this work as a Windows application icon?
Yes. The output is a standard ICO with PNG-compressed entries, which Windows has supported since Vista. Point a shortcut's Change Icon dialog at it, or reference it from your build configuration.