Can I make a favicon or ICO file from an image?

Yes, you can. Open your image in Paint by Zaweba, choose Save As and pick ICO, and Paint writes an icon file holding several sizes in one, which is what Windows and web browsers want. That gives you a favicon for a website or an icon for a program or shortcut, made offline and for free.

An ICO file is not just a small picture. It's a little bundle of the same image at different sizes, so the system can pick the right one for a browser tab, a taskbar or a desktop shortcut. A single tiny image scaled up looks blurred; several sizes in one file stay sharp everywhere.

Preparing the image

Start with a square image. If your logo is wide, put it on a square canvas with some space around it, by enlarging the canvas or starting a new square document. Icons are shown very small, so a detailed logo with fine text will turn to mush at the smallest sizes. The simple mark, a letter or a symbol, usually works better than the full logo.

Use a transparent background if the icon should sit on any colour. Delete or hide the background layer so the corners are empty. Then check how it looks small: zoom out until the image is about the size of a browser tab icon and see whether it still reads.

Saving the ICO

Choose File > Save As and select ICO. Paint stores the image at several sizes inside the one file. Save it with a clear name. For a website, the convention is favicon.ico in the root folder of the site, and most browsers will find it there on their own.

Keep the original as a .ptx or high resolution PNG too. If you need to change the icon later, you'll want to start from the big version rather than from the small sizes inside the ICO.

Getting sharp small icons

The smallest sizes are where icons fall apart. Thin lines vanish and edges go fuzzy. A few tricks help. Thicken strokes a little before saving. Increase contrast between the mark and its background. Line up straight edges with whole pixels so they don't sit across two rows and go soft. If your logo uses a gradient, check that it still reads as a shape when tiny, and use a flat colour if not.

You can also make a separate simpler version just for the smallest size, then use it as the source for the ICO. Many well-known app icons are drawn differently at small sizes for exactly this reason.

Other things people make with ICO files

Beyond favicons, ICO files are used for Windows shortcuts and folder icons, and for programs you build yourself. Paint opens ICO files as well as saving them, so you can open an existing icon, change it and save it again.

Paint by Zaweba is free software for Windows that opens and saves a long list of formats besides ICO, from PNG and JPEG to WebP, AVIF and TIFF, and it works without an internet connection or an account.