ICO Converter

Drop in an image file — JPG, PNG, BMP, or WebP — and the converter produces a multi-size ICO file ready for use as a favicon or desktop icon. Modern ICO format supports embedded PNG data at multiple resolutions inside a single container, so your output includes four size variants: 16×16 for browser tabs, 32×32 for standard desktop icons, 48×48 for shell shortcuts, and 64×64 for high-resolution displays.

The process runs in four steps. Step one loads your source image using the browser's image decoding pipeline, validating file type and size before any processing starts. Step two draws the image to four off-screen canvases, each scaled to a target ICO dimension using the browser's bilinear filtering. Step three encodes each canvas as a PNG blob — ICO containers can carry PNG data directly, which preserves quality better than older BMP-based ICO encoding. Step four assembles the ICO binary in memory, writing the ICONDIR header, per-image directory entries, and PNG payloads, then offers a direct download.

Practical tip: start with a square source image at 256×256 or larger so downscaling looks clean at all four sizes. Scaling up a small image produces blurry icons. All processing happens locally in your browser. Files are never uploaded to our servers.