Create a Multi-Size ICO from PNG
An ICO is more than a renamed image. It is a container that can hold several versions of the same icon, allowing Windows, desktop software, and browsers to select the resolution that fits the current display. This converter creates a real multi-size ICO file from your PNG instead of simply changing the filename.
Microsoft identifies 16×16, 32×32, 48×48, and 256×256 as the core sizes for Windows application icons. The smaller images stay crisp in lists, menus, and title bars, while the 256-pixel image supports large Explorer views. The optional 24, 64, and 128-pixel entries add useful intermediate resolutions.
PNG to favicon.ico
For a website favicon, the 16, 32, and 48-pixel preset covers common browser placements. Google Search accepts ICO favicons and recommends a square favicon larger than 48×48 pixels, so including a 256-pixel entry gives other surfaces a larger source to work with. After downloading, you can rename the file to favicon.ico, upload it to your site, and reference it in your page’s <head>.
Transparency and compatibility
Every resolution is stored as a 32-bit PNG image inside the ICO container. This keeps smooth alpha transparency and produces compact files for modern Windows versions and current browsers. Very old software that only understands BMP-encoded icon entries may need a legacy icon editor.
Your source image never leaves the device. The browser reads the PNG, draws each chosen resolution, constructs the ICO file locally, and starts the download. If you need to prepare the source first, use the Image Cropper to make it square or the Image Resizer to adjust its dimensions.