PNG to ICO converter (multi-size favicon)
Turn a PNG into a real multi-size .ico favicon — 16, 32, 48 and 256 px in one file — built in your browser with the link tags ready to copy.
- Runs in your browser
- Files are never uploaded
- Free, no account
What an .ico file really is
An ICO is a container, not an image. It starts with a six-byte directory header, followed by a sixteen-byte entry per image — width, height, colour depth, byte length and offset — and then the image payloads themselves. That is why a single favicon.ico can hold a 16-pixel version drawn for clarity and a 256-pixel version with full detail, and why every consumer picks the entry that suits it best rather than scaling one image on the fly.
Which size is used where
| Size | Used by |
|---|---|
| 16 × 16 | Browser tab, address bar, bookmark lists, history |
| 24 × 24 | Older Internet Explorer favourites bar |
| 32 × 32 | Taskbar, high-DPI browser tabs, desktop shortcuts |
| 48 × 48 | Windows desktop and Explorer medium icons |
| 64 / 128 | Intermediate scaling steps on high-DPI displays |
| 256 × 256 | Explorer “extra large icons”, Alt-Tab, jump lists |
The default selection — 16, 32, 48 and 256 — covers every one of those cases with a file that is normally well under 30 KB. Adding all seven sizes is harmless, just slightly larger.
PNG payloads, not BMP
Historically each entry inside an ICO was an uncompressed BMP-DIB with a separate one-bit transparency mask. Windows Vista added support for PNG payloads, and every browser and Windows version since reads them. We write PNG for a simple reason: a 256 × 256 BMP entry is 256 KB of raw pixels, while the same image as PNG is usually a few kilobytes. If you need to support Windows XP specifically, leave 256 out of the selection — XP will still find the smaller entries it understands.
Designing an icon that survives 16 pixels
- Simplify. A 16 × 16 grid holds 256 pixels in total. Wordmarks, gradients and thin outlines all vanish; a single bold glyph or shape does not.
- Crop the padding. Logos usually ship with generous whitespace. Trim it before uploading here, otherwise your icon is a small mark floating in an empty square.
- Maximise contrast. The icon will be seen against both a light and a dark browser theme. A mid-grey mark disappears against one of them.
- Start at 512 or 1024 px. Downscaling from a large clean source with a Lanczos filter, as this tool does, gives far better small sizes than upscaling from a 64 px original.
Non-square logos
Icons are square by definition. With padding switched on, a wide logo is centred in a square canvas — transparent by default, or filled with a colour if you type a hex value. With padding off, the image is stretched to a square, which distorts nearly everything. If your brand mark is strongly horizontal, consider making a separate square version (an initial, a symbol) rather than squeezing the full logo into a favicon.
Installing the favicon
Put the file at the root of your site as /favicon.ico. Browsers request that exact
path even when no link tag is present, which is why it is still the most reliable fallback.
Then add the explicit tags — the tool gives you them to copy — so you can also offer a scalable
SVG icon and an Apple touch icon for iOS home screens. If the old icon persists after you
deploy, that is browser caching: try a hard reload, or a private window, before assuming
something is wrong.
Built here, not on someone's server
The resize, the PNG encoding and the ICO directory assembly all happen in this tab. That is unusual for favicon tools, which are typically ad-supported upload services — and it means your unreleased brand mark is not sitting in someone's temporary directory. It also means there is no queue: change the size selection and rebuild instantly.
Related tools
ICO to PNG for the reverse direction, Favicon Generator for the full set of PNG sizes and the web app manifest, and Resize Image if you need to prepare the source first.
Questions
Why does an .ico need several sizes?
Because different places pick different layers out of the same file: 16 px for the browser tab and address bar, 32 px for the taskbar and high-DPI tabs, 48 px for the Windows desktop, and 256 px for Explorer’s large-icon view. One 256 px image scaled down on the fly looks muddy at 16 px.
Are the images inside stored as PNG or BMP?
PNG. Windows XP and every later version read PNG payloads inside an ICO container, and PNG is far smaller than the old BMP-DIB layout — a 256 px BMP entry alone would be 256 KB.
My logo is not square. What happens?
By default it is padded to a square so the proportions survive, with a transparent background unless you type a colour. Turning padding off stretches the image to a square instead, which distorts most logos.
Where do I put the file?
At the root of your site as /favicon.ico — browsers request that path even with no link tag. Adding the explicit tags shown on the page also lets you offer an SVG icon and an Apple touch icon alongside it.
Is anything uploaded?
No. The resize, the PNG encoding and the ICO directory are all built in the page, which is worth noting given how many favicon generators are ad-funded upload services.