Convert PNG to ICO

How to use it#

1. Drop a PNG onto the box above, or click it to pick one. A JPG, WebP, SVG, or ICO works as well.
2. Tick the sizes to put in the icon. It starts on 16, 32, and 48 pixels, which is what a favicon needs.
3. Check the file size in the figures beside the icons, then download the ICO.

Which sizes to put in the ICO file#

An ICO file holds the same icon at several sizes, and whatever shows it picks the one that fits. A browser tab draws a favicon at 16 pixels, or 32 on a high density screen, and Windows uses 48 for medium icons in a folder. Those three are ticked to start with, and they cover a favicon.

The larger sizes are for a Windows program or shortcut icon. Windows uses 256 for its largest icon views and scales it down for the sizes in between, so 64 and 128 matter only if you want those views to have a picture of their own. Each size you add makes the file bigger, and 256 usually outweighs all the small ones together, so the file size in the figures changes as you tick.

Each tile shows the picture as it will look at that size. A detailed logo often turns to mush at 16 pixels. Better to see that here, and simplify the logo, than in a browser tab after it goes live.

A picture that is not square#

Every picture in an ICO file is square. A wide or tall picture is scaled to fit the square and centred, with transparent space filling the rest, so none of it is cut off or squashed. The page says when this has happened and on which sides the space went.

If you would rather the picture filled the square, cut it to a square first with the image cropper, using its square shape, and convert the result. For a logo on a coloured background you want to lose, make the background transparent first.

Which files work, besides PNG#

A JPG, WebP, GIF, AVIF, or BMP converts the same way as a PNG. A JPG has no transparency, so its background stays as it is. A GIF gives its first frame.

An SVG is drawn at 512 pixels before the sizes are made from it, so even the 256 pixel size comes out sharp. When a PNG is smaller than one of the sizes, that size has to be scaled up and looks soft. The page tells you which sizes that applies to.

An existing ICO file works too. Its largest picture is used, and the sizes are drawn again from it, which is how to add a 256 pixel size to a favicon.ico or strip one out. To get the pictures out of an icon as PNGs instead, use ICO to PNG.

What is inside the file#

Each size is stored as a PNG inside the ICO, with its transparency, which is how icons have been written since Windows Vista and what every current browser reads. The file is exactly the PNGs plus a sixteen byte entry for each, so the size shown is the size you download.

Windows XP and older read only the older bitmap entries, which this page does not write.