Converting BMP to ICO produces Windows icon files. BMPs are historically the native source format for icon creation; many icon tools export BMPs before packing them into ICO containers.
Drag & drop image files here, or browse
Drop your BMP files here
Standard icon sizes (16, 32, 48, 256) are generated by downscaling the BMP. Alpha transparency transfers if the source is 32-bit BMP. For transparent icons a 32-bit BMP source or a PNG source works best.
ICO is the native Windows icon format, universally supported by browsers and Windows tools.
BMP is the uncompressed Windows bitmap format from 1990. Files are huge because almost nothing is compressed, but the format is trivial to decode and supported by virtually every Windows utility, embedded system, and legacy tool. Useful as an interchange format when other options fail.
ICO is the Windows icon format. A single .ico file can hold multiple resolutions (16×16, 32×32, 48×48, 256×256) and color depths simultaneously, letting the OS pick the best for context. Every browser serves favicons as ICO, and Windows desktop icons use it natively.
Only if the BMP is 32-bit with an alpha channel. 24-bit BMPs produce opaque icons with no transparency.
256×256 or larger, square. Smaller sources can't be meaningfully upscaled to sharp large icons.
BMP is the uncompressed Windows bitmap format from 1990. Files are huge because almost nothing is compressed, but the format is trivial to decode and supported by virtually every Windows utility, embedded system, and legacy tool. Useful as an interchange format when other options fail.
ICO is the Windows icon format. A single .ico file can hold multiple resolutions (16×16, 32×32, 48×48, 256×256) and color depths simultaneously, letting the OS pick the best for context. Every browser serves favicons as ICO, and Windows desktop icons use it natively.
Yes. The converter runs entirely in your browser using WebAssembly. Your images are never uploaded, never sent to a server, and never leave your device.
There's no hard limit, but because everything runs in your browser you're bounded by available memory. Very large images (over a few hundred megapixels) can hit browser memory limits. Process in smaller batches if you run into issues.