How to use it
- Add BMP files.
- Choose a quality. 90% is a good default.
- Download the JPGs and compare the sizes.
Why BMP files are so large
A standard 24-bit BMP stores three bytes for every pixel, with no compression at all. The maths is simple: a 1920 × 1080 image is just over two million pixels, times three bytes, which is about 5.9 MB, regardless of what the picture shows. A JPG of the same image is often 300 to 600 KB.
BMP still turns up from old scanners, industrial and lab equipment, legacy Windows programs, and screenshots from some older software. None of those need to stay as BMP once you have them.
JPG or PNG?
If the BMP is a photograph or a scan of a photo, JPG is right. If it is a screenshot, diagram, chart or anything with text, BMP to PNG will keep the edges perfectly sharp and still shrink the file a lot, because PNG compresses flat areas very efficiently.
BMP and JPG compared
| BMP | JPG | |
|---|---|---|
| First released | 1985 | 1992 |
| Compression | Usually none | Lossy |
| Transparency | Rarely | No |
| Animation or pages | No | No |
| Best for | Older Windows software and devices | Photos for sharing, email and print |
| Support | Most desktop software | Universal |
Questions people ask
How much smaller will the file get?
For photos, commonly 90 to 95 percent smaller. The exact saving depends on the image and quality setting.
Are there different kinds of BMP?
Yes, including 1, 4, 8, 24 and 32-bit versions, some with simple compression. Your browser reads all the common ones.
Is quality lost converting BMP to JPG?
A small amount, since JPG is lossy. At 90% it is rarely visible. Use PNG if you need a lossless result.