BMP to WebP Converter

BMP is an uncompressed raster format developed by Microsoft for Windows. A 1920×1080 pixel BMP file stores approximately 6 MB of raw pixel data with no compression applied. The same image encoded as WebP at quality 90 typically occupies 150 to 300 KB — a reduction of 95 percent or more without perceptible visual loss.

This converter decodes the BMP in the browser using the Canvas API and re-encodes it as WebP. No file is uploaded to any server.

Why BMP Files Are So Large

BMP stores every pixel as a fixed-width value — typically 24 bits for RGB or 32 bits for RGBA — with no attempt to find repeated patterns or remove imperceptible information. The format was designed for direct memory-mapped display on Windows systems in the 1980s, where decompression overhead mattered more than storage efficiency.

Modern web and storage contexts invert those priorities completely. Network bandwidth and storage cost per byte are the operative constraints, and a format that allocates the same bytes to a flat blue sky as it does to fine photographic detail is poorly suited to either.

BMP files also lack metadata optimisation, progressive loading support, and the sub-sampling schemes that allow JPEG and WebP to prioritise human-visible frequency information over imperceptible high-frequency data.

BMP vs WebP: Format Comparison

Quality Settings for BMP to WebP

The quality slider controls the WebP encoder’s lossy compression level. BMP sources decoded from raw pixel data contain no pre-existing compression artefacts, so the WebP output quality is determined entirely by the slider value applied during this conversion.

Quality 90 is a strong default for photographic BMP sources — output is visually indistinguishable from the original at typical screen viewing distances while achieving file size reductions of 90 to 95 percent. For graphics with flat colour, logos, or illustrations, quality 80 reduces file size further without visible loss on flat regions.

How the Converter Works

Drop or select your BMP file. The browser decodes the raw pixel data using its built-in BMP parser, draws the image to an offscreen canvas element, and re-encodes it as WebP at your chosen quality. The WebP file downloads directly from browser memory to your device. Nothing is transmitted to any external server.