PNG to ICO,
transparency and all.

Transparency is the whole reason to start from PNG

Browser tab strips are not one colour. They are light in one theme, near-black in another, and different again when a tab is pinned or the window is inactive. An icon built from a source with a baked-in background shows that background as a rectangle sitting inside the tab. An icon built from a transparent PNG does not, because the alpha channel travels into the .ico and every size inside it stays see-through.

That is the practical difference between starting here and starting from a photo or a flattened export. If your logo only exists as a JPG, the JPG to ICO page covers that route and explains what an .ico container holds, but the white box behind your mark is baked in before Squish ever sees it.

Do you still need a .ico at all?

Reasonable question, and the answer is a qualified yes. Modern sites usually declare PNG icons in the page head and in a web app manifest, and browsers happily use them. But every browser still makes an unprompted request for /favicon.ico at your domain root, whether you reference it or not. Serving one means that request finds something instead of logging a 404, and it is the only icon that works with no markup at all. Treat the .ico as the floor, not the whole strategy.

Common questions

Why does my logo turn to mush at 16px?

Because 16 by 16 is 256 pixels in total, and detail that reads fine on a website simply has nowhere to go. Wordmarks, thin strokes and gradients all suffer. The fix is not a better converter, it is a simpler source: crop to the mark rather than the full lockup, drop the tagline, and thicken hairlines before you convert. Squish scales what you give it faithfully, which means it will faithfully scale down something that was never going to survive.

Which sizes end up inside the file?

16, 32, 48 and 256, each stored losslessly, minus any size larger than your source. Drop in a 64px PNG and you get a three-size icon rather than a blurry upscale. If you want all four, start from something at least 256px square.

What happens to a logo that is not square?

It is centred and padded with transparent space rather than cropped or stretched, so a wide wordmark keeps its proportions and simply sits in a shorter band inside the square. Nothing is cut off.

Where do my files go?

They are processed in memory and never stored. Nothing is kept once the .ico comes back to you.