Image to ICO Converter

What is an ICO File?

An ICO file is a container format used primarily for website favicons and Windows application icons. Unlike standard image formats such as PNG or JPEG, a single ICO file can hold multiple image sizes and resolutions inside one file. This allows the operating system or browser to pick the most appropriate size for its context — a 16×16 icon for a browser tab, a 32×32 icon for a bookmark bar, or a 256×256 icon for a desktop shortcut.

The ICO format dates back to Microsoft Windows 1.0 and has remained the standard icon format for the Windows platform. On the web, the /favicon.ico convention is still universally supported by all major browsers as a fallback when no <link rel="icon"> tag is present in the HTML.

How to Convert an Image to ICO

1. 1.
   Upload your image — Drag and drop or click to select a PNG, JPG, SVG, or WebP file. For the best results, use a square image at least 256×256 pixels.
2. 2.
   Choose your sizes — Select which icon sizes to include in the ICO file. The defaults (16, 32, 48) cover most browser and OS use cases. Add larger sizes like 128 or 256 for high-resolution displays and Windows desktop icons.
3. 3.
   Download the ICO file — Your converted icon is generated entirely in the browser. Nothing is uploaded to any server, so your images stay private.

ICO File Best Practices

• •
  Always include 16×16 and 32×32 — These are the two sizes browsers look for first. The 16px variant appears in tabs, while the 32px variant is used in bookmark bars and history lists.
• •
  Add 48×48 for Windows taskbar — Windows uses the 48px size for taskbar icons and Alt+Tab previews. Omitting it forces the OS to scale down a larger image, which may look blurry.
• •
  Use 256×256 for Windows Vista+ — Modern Windows versions display 256px icons in explorer's large/extra-large icon views. This layer is typically stored as a compressed PNG inside the ICO to keep file size manageable.
• •
  Start with a square source image — ICO files expect square dimensions. If your source image is not square, it will be stretched to fit, which can distort the result.
• •
  Keep file size in check — An ICO with all sizes from 16 to 256 typically weighs 50-150 KB. For web favicons where loading speed matters, including only 16, 32, and 48 keeps the file under 10 KB.
• •
  ICO vs PNG for favicons — Modern browsers support PNG favicons via <link rel="icon" type="image/png">, but the /favicon.ico path remains the universal fallback. For maximum compatibility, provide both.

Frequently Asked Questions

Is this tool free to use?

Yes, completely free with no limits. The conversion runs entirely in your browser using JavaScript — no server processing, no uploads, no sign-up required.

What image formats can I convert?

You can convert PNG, JPEG, WebP, and SVG files. For best quality, use a PNG or SVG source image with transparency support.

Why include multiple sizes in one ICO file?

Different contexts require different icon sizes. A browser tab uses 16×16px while a Windows desktop shortcut needs 256×256px. Bundling multiple sizes ensures your icon looks sharp everywhere without the system having to scale it.

Does this preserve transparency?

Yes. If your source image has transparent areas (PNG or SVG with alpha channel), the transparency is preserved in the generated ICO file.

Can I use the ICO file as a Windows application icon?

Yes. ICO is the native icon format for Windows executables and shortcuts. For application icons, include the 256×256 size for the best experience in modern Windows explorer views.