β Image to ICO Converter
Turn any image into a Windows .ico icon with 16, 32, and 48 px sizes.
How to Convert an Image to ICO
Upload a square PNG or JPG, keep the sizes you need checked, and convert. The tool renders your image at 16, 32, and 48 pixels, encodes each as PNG, assembles a valid .ico file in your browser, and hands you the download.
Upload a square image. Simple, bold designs read best at tiny sizes.
Choose icon sizes. All three checked covers favicons and app icons.
Click Convert to ICO, preview each rendered size, then download.
Use as favicon.ico in your site root with a link rel="icon" tag.
Inside the ICO Format
An ICO file starts with a 6-byte header declaring the icon type and how many images follow. Each image gets a 16-byte directory entry recording its width, height, color depth, and the byte offset where its data lives. Modern icons store each size as a complete PNG file, which the operating system decodes on demand: this PNG-compressed style has been standard since Windows Vista and is what this tool produces. Keeping multiple sizes matters because a single 16-pixel image scaled up looks blurry, while a 48-pixel image scaled down can shimmer; embedding purpose-rendered sizes lets each context use pixels drawn exactly for it. The 16-pixel entry is what you see in browser tabs, the 32-pixel one in dialogs and the taskbar, and 48 in explorer views and high-DPI displays. All rendering here uses high-quality smoothing so diagonal edges stay clean at every size.
Favicon Best Practices
Design for 16 pixels first: if it reads at tab size, it reads everywhere. Avoid text, which becomes illegible mush below 32 pixels; use a single glyph or abstract mark instead. Keep generous contrast between the mark and its background so it survives both light and dark browser themes. Test the downloaded icon in an actual tab, because preview scaling in design tools can mislead. For modern sites, also consider shipping an SVG favicon and a 180-pixel apple-touch-icon alongside the ICO, since mobile browsers prefer those; the ICO remains the safe universal fallback that every browser understands.
Frequently Asked Questions
What is an ICO file?
ICO is the Windows icon container format. A single .ico file can hold multiple images at different sizes and color depths, and Windows picks the best one for each context: taskbar, desktop, file explorer, or title bar. This tool embeds 16, 32, and 48 pixel PNG-compressed images, which covers favicons and most app icon uses.
How do I use the ICO as my website favicon?
Download the .ico file, place it in your website root folder, and add <link rel="icon" href="/favicon.ico"> inside the <head> of your pages. Browsers request /favicon.ico by default even without the tag. For best results start from a square source image with a simple, bold design that stays readable at 16 pixels.
What image should I start from?
Use a square PNG with a simple design and strong contrast. Fine detail disappears at 16 by 16 pixels, so bold shapes and limited colors work best. If your source is not square, it is centered and scaled to fit, which may add padding: crop to a square first with our Image Cropper for full control.
Which sizes are included in the ICO?
The generated file contains 16x16, 32x32, and 48x48 pixel images, each PNG-compressed per the modern Vista-style icon format. 16 is the browser tab and taskbar size, 32 appears in file dialogs and larger views, and 48 covers desktop and high-DPI contexts.
Does transparency survive the conversion?
Yes. The source is drawn to each size and encoded as PNG inside the ICO, preserving the alpha channel. Semi-transparent edges stay smooth. If you convert from JPG, which has no transparency, the icon gets a solid background instead, so prefer PNG sources for icons.
Is my image uploaded anywhere?
No. Resizing, PNG encoding, and ICO assembly all happen in your browser with JavaScript. Your artwork never leaves your device, and the generated ICO works in every browser and Windows version. Your design choices remain entirely your own. Re-run with different sizes anytime without re-uploading to a service.