What is BMP to PNG conversion?
This tool converts BMP images into the PNG format, entirely in your browser with no upload. BMP is an uncompressed bitmap format from Windows. Files are very large because pixels are stored raw, so converting to PNG or JPG usually shrinks them dramatically. PNG is a lossless format with transparency support, so quality never degrades when you save. It is ideal for logos, icons, screenshots with text and images with transparent backgrounds, but files tend to be larger.
How to use it
- Select or drop in your BMP image.
- The tool converts it to PNG locally, instantly.
- Click Download to save the PNG file.
When should you convert BMP to PNG?
BMP files are uncompressed and huge, usually exported by older Windows programs.
Convert BMP to PNG when you need lossless quality or a transparent background — for cut-outs, logos or assets you will edit further. The trade-off is that PNG files are usually larger than BMP.
BMP vs PNG: key differences
| Property | BMP | PNG |
|---|---|---|
| Compression | Lossless | Lossless |
| Transparency | No | Yes |
| Best for | Raw, uncompressed Windows bitmaps | Logos, icons, screenshots, transparent graphics |
Shrinking a huge BMP into a web-ready PNG
A BMP straight out of an old program or MS Paint has no compression at all, so a single image can run to several megabytes—far too heavy to drop onto a web page. Converting to PNG is the natural move: it's still lossless, so nothing degrades, yet the file gets dramatically smaller, and it supports transparency. Great for screenshots, icons, and line art.
- PNG shrinks things a lot, but it's still lossless, so photographic content can stay fairly large.
- If that BMP is actually a photo, convert it to JPG instead—it'll be far smaller and better suited to the web.
Why does the same BMP shrink 99% sometimes and only 18% others?
A BMP barely compresses at all, which is why all three test files are exactly the same size (2.75 MB each) — it records width × height × channels and nothing about what is in the picture. The difference happens entirely on the output side: the illustration becomes 40.6 KB (-99%), the screenshot 22.9 KB (-99%), while the photo only reaches 2.25 MB (-18%). PNG compresses by predicting a pixel from its neighbours, and photographic grain is unpredictable by nature. So this conversion is nearly free money for scanned documents, charts and line art; for a photograph you get a lossless file that is still large, and that is the moment to consider JPEG or WebP instead of PNG.