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Convert PNG to ICO

Files never leave your device. All processing happens in your browser.

How to convert PNG to ICO

  1. 1

    Drop in a square PNG — 256×256 or larger gives the best result.

  2. 2

    Six sizes are rendered and packed into one icon file.

  3. 3

    Download favicon.ico and put it at the root of your site.

An ICO is not really an image format so much as a small archive. A single .ico file holds the same picture at several resolutions, and whatever is displaying it picks the one that fits — 16 pixels for a browser tab, 32 for a taskbar, 256 for a large icon view in Explorer. That is the whole reason the format still exists.

What this produces

Six sizes: 16, 32, 48, 64, 128 and 256 pixels square, each stored as PNG data inside the container. 256 is the maximum an ICO can describe, because the width and height are recorded as single bytes with zero standing in for 256. Every browser and every version of Windows still in use reads PNG-in-ICO, so there is no reason to fall back to the older uncompressed layout.

The result is a favicon.ico you can drop at the root of a website and forget about. Browsers request that path automatically even with no markup pointing at it, which is why the file remains worth producing despite modern sites also declaring PNG and SVG icons.

Start from something square and simple

  • Use a square source. A non-square image is fitted inside the square and centred rather than stretched, which leaves empty margins.
  • Supply at least 256×256. Anything smaller gets scaled up for the large entries and looks soft.
  • Simplify the artwork. At 16 pixels a detailed logo becomes an unreadable smudge — most good favicons are a single letter or one bold shape.
  • Keep the transparency. It carries through, so the icon sits cleanly on light and dark browser themes alike.
  • Test at 16 pixels before committing. That is the size almost everyone actually sees.

Why the file is a few tens of kilobytes

Six images in one container adds up, and the 256-pixel entry accounts for most of it. That is normal for a multi-size icon and is not worth optimising: the file is fetched once and cached aggressively by every browser. If you genuinely need it smaller, a 16/32/48 icon covers the common cases, though large-icon views in Explorer will then scale up a 48-pixel image.

ICO is not the whole story any more

Modern sites usually declare several icons: an SVG for browsers that support one, a couple of PNGs for Apple touch icons and Android home screens, and the ICO underneath it all. The ICO is the fallback that needs no markup, works in older browsers, and is what Windows uses for pinned sites and desktop shortcuts. It is still worth having, but it is no longer the only file you want.

The whole thing is assembled in this tab. The container is written byte by byte in JavaScript on your own machine — no library and no server involved — so an unreleased brand mark never leaves your device.

Questions about PNG to ICO

What sizes does the icon contain?

Six: 16, 32, 48, 64, 128 and 256 pixels square. That covers browser tabs, bookmarks, the Windows taskbar, desktop shortcuts and large icon views, and 256 is the largest an ICO file can describe.

Where do I put the file?

At the root of your site as favicon.ico. Browsers request that path automatically even without a link tag in your HTML, which is why the format is still worth producing.

Does transparency work in an ICO?

Yes. Each size is stored as PNG data with a full alpha channel, so the icon has clean edges on both light and dark browser themes.

My source image is not square. What happens?

It is scaled to fit inside the square and centred, leaving transparent margins on two sides, rather than being stretched out of proportion. A square source avoids the margins.

Why does my detailed logo look like a smudge?

At 16 pixels there are only 256 pixels in total to work with. Detailed artwork cannot survive that. Effective favicons are usually a single letter or one bold, simple shape.

Do I still need an ICO if I have PNG icons?

It is still worth having. Browsers fetch /favicon.ico by default, some older ones prefer it, and Windows uses it for pinned sites and shortcuts. It costs one small cached file.

Can I use a JPG as the source?

Yes, the tool accepts JPG, WebP, GIF and BMP as well as PNG. But a JPG has no transparency, so the icon will have a solid rectangular background unless you convert it to PNG and remove the background first.

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