BMP to JPG
Convert BMP to JPG to turn a bulky Windows bitmap into a file small enough to email, upload or keep.
How the files you choose are handled is set out in the privacy policy.
How to convert BMP to JPG
- Tap Choose BMP files and select one or more files.
- Leave the quality on High. Even so, the JPG will be a small fraction of the BMP.
- Press Convert to JPG, then save the picture, or all of them as one ZIP.
Why BMP files are so large
BMP, the Windows bitmap, dates from the 1980s and usually stores a picture with no compression at all: three bytes for every pixel, row after row. The size depends only on the dimensions, not on what the picture shows. A blank white page takes exactly as much room as a detailed photograph.
| Picture size in pixels | As BMP | As JPG, High quality |
|---|---|---|
| 800 × 600 | 1.4 MB | about 100 to 200 KB |
| 1920 × 1080 | 5.9 MB | about 300 to 600 KB |
| 4000 × 3000 | 34 MB | about 3 to 5 MB |
The BMP figures are exact arithmetic: width times height times three. The JPG figures depend on the picture.
Where BMP files still come from
- Older scanners and their software.
- Microsoft Paint, when the save type was left on bitmap.
- Screenshots from old Windows versions and from some games.
- Industrial cameras, microscopes, lab instruments and embedded devices, which favour BMP because it is trivial to write.
JPG or PNG for a bitmap?
Both make the file far smaller. Which is better depends on the content.
- Photographs and scans of photos: JPG. It is the smallest by a wide margin.
- Screenshots, diagrams, drawings from Paint, scanned text: PNG keeps every pixel exactly and still shrinks these a great deal, because flat areas pack well. Change Convert to to PNG before converting.
If you are unsure, convert one file each way and compare.
What stays the same
The size in pixels does not change unless you pick a smaller one. Colours are kept. At High quality a JPG of a photographic bitmap is very hard to tell from the original, even side by side.
Unusual bitmaps
BMP has many variants: 1, 4, 8, 16, 24 and 32 bits per pixel, some with simple compression. Browsers read the common ones. If a particular file is reported as unreadable, it is probably a rare variant, and opening and re-saving it in Paint usually fixes that.
After converting, compress image can take a JPG down to a set number of kilobytes, and resize image changes its dimensions.
Questions
How much smaller is a JPG than a BMP?
Usually ten times smaller or more. A 5.9 MB full HD bitmap becomes a JPG of a few hundred kilobytes.
Does converting BMP to JPG reduce quality?
Very slightly. At High quality the difference is not visible on photographs.
Should I convert a BMP to JPG or PNG?
JPG for photos. PNG for screenshots, drawings and text, where edges need to stay crisp.
Is a BMP better quality than a JPG?
It is exact, where a JPG is a close approximation. For viewing and sharing, the difference is not something you can see.
Why would anyone use BMP?
It is extremely simple, so old software and laboratory or industrial devices still produce it.