Convert BMP to GIF — Free Online Converter

BMP stores raw 24-bit uncompressed pixel data (16.7 million colors), while GIF uses LZW compression limited to a 256-color indexed palette. Converting BMP to GIF applies aggressive color quantization, reducing the color space from millions of colors to at most 256, then compresses the result with LZW encoding. The resulting file is dramatically smaller than the BMP but at the cost of color fidelity.

This conversion makes sense for simple BMP graphics with limited colors — icons, diagrams, screenshots of terminal output, and pixel art — that need to be distributed via the web or messaging platforms. For these content types, the 256-color limit is rarely a visible constraint, and the file size reduction from uncompressed BMP to compressed GIF can be 10-50x.

BMP files are impractically large for web delivery, email, and messaging. A 1920x1080 BMP occupies nearly 6 MB, while the same image as GIF (if suitable content) might be 50-200 KB. For sharing simple graphics, diagrams, and icons, GIF provides a universally supported format at a tiny fraction of BMP's file size.

Legacy web platforms and older email systems handle GIF more reliably than modern formats. Some older content management systems, forum software, and email clients display GIF inline but struggle with PNG or WebP. When sharing BMP-sourced graphics in these legacy environments, GIF provides the most compatible web format.

Sharp decodes the BMP's raw 24-bit RGB pixel data, applies median-cut color quantization to reduce the palette to 256 or fewer colors, and encodes the result with LZW compression in GIF89a format. Optional Floyd-Steinberg dithering distributes quantization error to reduce visible banding. Since BMP does not support transparency, no alpha handling is needed — the GIF output is fully opaque unless a specific color is designated as transparent.