How to Convert an Image to ICO
ICO is not really an image format so much as a container— a single file holding the same icon at several different resolutions, so the operating system can pick whichever one fits the space it needs to fill. That is the whole point of it, and it is precisely what most online converters skip. This tool writes a genuine ICO binary with every size you choose embedded inside, rather than renaming a PNG and hoping for the best.
Upload your image
A square PNG with transparency gives the cleanest icon. It is processed entirely on your device.
Choose the sizes
Use a preset, or tick exactly the resolutions you need. Each is rendered separately at that size.
Download the .ico
One file containing every size, ready to drop into a website root or use as an application icon.
Why a Renamed PNG Is Not an ICO
Changing a file's extension changes nothing about its contents. A PNG called favicon.icois still a PNG, and while some browsers are forgiving enough to display it anyway, plenty of software is not — Windows Explorer, installer builders, older browsers and desktop application frameworks all expect the real structure and will simply fail.
A genuine ICO begins with a small header stating how many images it contains, followed by one directory entry per image recording its dimensions, colour depth, size in bytes and where in the file it starts. Only then comes the actual image data. This tool builds that structure properly, embedding PNG data inside each slot— the modern approach, which every current operating system reads and which keeps the file far smaller than the old uncompressed bitmap method.
The practical benefit of multiple sizes is sharpness. When Windows shows your icon in a 16-pixel taskbar slot, it uses the 16-pixel version you supplied — drawn deliberately at that size — rather than crushing a 256-pixel image down and producing a blurry mess. Each size in this tool is rendered from your source independently, which is why they all look crisp.
Which Sizes Do You Actually Need?
16, 32 and 48 for a website favicon
These are the sizes browsers request. Sixteen for the tab, thirty-two for bookmarks and high-density displays, forty-eight for shortcuts. Anything larger is dead weight in a favicon.
Add 256 for Windows applications
Windows uses 256-pixel icons for large tile views and file previews. Without it, Explorer upscales a smaller version and it looks noticeably soft.
Design for the smallest size first
If your mark is unreadable at sixteen pixels, no amount of larger sizes will help - that is the one people see all day in a tab bar. Simplify until it works there.
More sizes means a bigger file
Every embedded resolution adds its own image data. Ticking everything produces a file several times larger than one holding just the three sizes you need.
Frequently Asked Questions
How do I convert a PNG to ICO for free?
Upload your image, tick the sizes you need, and download. Free, no signup, and it produces a real multi-size ICO file.
Is this a real ICO or a renamed PNG?
A real ICO binary with a proper header and directory structure, containing every size you selected. Renamed PNGs fail in Windows Explorer, installers and older browsers.
Which sizes should I include?
16, 32 and 48 for a website favicon. Add 256 for a Windows application icon. Only include what you need, since each size adds to the file.
Does it keep transparency?
Yes. Each embedded image is 32-bit with a full alpha channel, so transparent areas stay transparent at every size.
Why does my icon look blurry at small sizes?
Usually because the artwork has too much detail. At sixteen pixels only a simple, high-contrast mark survives - fine lines and text turn to mush.
Is my image uploaded to a server?
No. The ICO file is assembled byte by byte inside your browser. Your image is never uploaded, stored or seen by anyone.
What image should I start with?
A square PNG with transparency, at least 256 pixels. Square avoids distortion, and starting large means every size is scaled down rather than up.
What is the difference between this and a favicon generator?
This produces a single .ico file. A favicon generator also produces the separate PNG sizes, apple-touch-icon and manifest that a modern website needs alongside it.
Can I use a photo as an icon?
You can, but photographs have far too much detail to read at icon sizes. A flat graphic mark works far better.
Where do I put the favicon.ico file?
In the root directory of your website. Browsers request it from there automatically, even without any HTML pointing to it.
What is the padding option for?
It insets your artwork so it does not touch the icon edges. Useful when the source image is tightly cropped and looks cramped as an icon.
Is this ICO converter really free?
Completely free, with no limits, no watermark, no signup and no premium wall. Everything runs in your browser.
Last updated: July 21, 2026 · FlipMyFormat ICO Converter
Written and maintained by the FlipMyFormat team