BMP to JPG Converter

BMP (Bitmap) is Microsoft's original Windows image format, introduced in 1985 and still produced by Windows system components, older scanner drivers, some hardware devices, and legacy enterprise software. BMP stores every pixel as raw, uncompressed RGB data: a 1920×1080 BMP at 24-bit color is exactly 5.93 MB, always, regardless of what the image shows. A photograph, a solid white rectangle, and a screensaver frame all produce the same file size because BMP does no compression whatsoever. Converting to JPG reduces that 5.93 MB file to 100–400 KB at quality 85 — a 90–98% reduction — with no visible change in the image.

The AT USE BMP to JPG Converter processes files server-side using ImageMagick. Upload a BMP file up to 20 MB, set the output quality, and download the compressed JPG immediately. Both files are deleted from the server the moment your download completes.

Why BMP files are so large

BMP's size comes from its simplicity. A 24-bit BMP stores exactly 3 bytes per pixel: one byte each for red, green, and blue. There is no entropy coding, no predictive compression, no frequency-domain transform — just raw pixel values written row by row to disk. This makes BMP trivially easy to implement in hardware and low-level software (which is why the format still appears in device drivers and system components) but makes it impractical for storage or transmission where file size matters. A camera photograph at 12 megapixels stored as BMP would be 34 MB. The same photo as JPG at quality 85 is under 3 MB.

What the conversion does

Converting BMP to JPG is the first lossy compression applied to this pixel data — BMP had no prior compression, so there is no cumulative degradation from a previous lossy step. The JPEG encoder reads the raw BMP pixel grid and applies its Discrete Cosine Transform compression. Because the source is pristine uncompressed data, quality 80–85 gives excellent JPG output with very small files. This is different from converting a previously compressed JPG to JPG again (where quality loss accumulates). Converting from BMP to JPG at quality 85 is a clean, single first-pass compression that gives you the full quality benefit of JPEG encoding.

Transparency in 32-bit BMP

Standard BMP files are 24-bit (RGB with no transparency). Some applications save 32-bit BMP files that include an alpha channel — the fourth byte per pixel stores opacity. JPEG has no alpha channel, so the transparent pixels in a 32-bit BMP are composited against a white background before JPEG encoding. The result is a flat image with white fill where the original had transparency. For 32-bit BMP sources where transparency must be preserved, use the BMP to PNG converter instead.

Typical BMP sources

Windows Paint and the older Windows Snipping Tool both saved files as BMP by default until Windows 10 and 11 changed the defaults to PNG. Windows desktop backgrounds saved through older versions of Internet Explorer, screenshots taken by industrial hardware systems, images captured by medical imaging equipment, and exports from CAD or GIS software all commonly produce BMP output. Older scanners running manufacturer drivers from before 2010 often default to BMP unless reconfigured. If you are opening BMP files in your workflow, the source is almost certainly one of these legacy contexts.