Where BMP files still turn up
BMP dates back to early versions of Windows and OS/2. It is rarely chosen deliberately today, but it still appears in several places: older scanners and scanning software that save BMP by default, screenshots from legacy Windows applications, industrial and medical equipment, embedded systems and old games, and image exports from software written decades ago. If you have such files and need to email them, upload them to a website or store them efficiently, converting to JPG is the quickest fix.
How much space you save
| Image | BMP (24-bit) | JPG (quality 90) |
|---|---|---|
| 1920 × 1080 screenshot | about 6 MB | 200–600 KB |
| 3000 × 2000 scanned photo | about 18 MB | 1–2 MB |
| 800 × 600 image | about 1.4 MB | 60–150 KB |
The exact JPG size depends on how much detail the image contains, but savings of 90% or more are normal.
How the conversion works
BMP files are decoded by your browser’s built-in image decoder inside a background Web Worker, which handles the common BMP variants (24-bit and 32-bit, top-down and bottom-up). The pixels are then encoded with MozJPEG at the quality you choose. If a 32-bit BMP contains an alpha channel, transparent areas are filled with white. Nothing is uploaded.
When to choose PNG instead
JPG is ideal for photographic content such as scanned prints. For BMP screenshots of software, diagrams or pixel art, JPG can introduce faint smudges around sharp edges and text. In those cases, use the image converter with PNG as the output: it is still lossless like BMP but typically five to ten times smaller.
Batch conversion for archives
If you are cleaning up an old archive of scans or screenshots, drop the whole folder in at once. Files are processed in parallel and can be downloaded together as a ZIP, ready to replace the bulky originals.