What is BMP to WebP conversion?
This tool converts BMP images into the WebP 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. WebP is a modern web format from Google that supports both transparency and higher compression, typically 25–35% smaller than JPG or PNG. It is great for speeding up websites, though a few older programs may not support it.
How to use it
- Select or drop in your BMP image.
- The tool converts it to WebP locally, instantly.
- Click Download to save the WebP file.
When should you convert BMP to WebP?
BMP files are uncompressed and huge, usually exported by older Windows programs.
Convert BMP to WebP when you want faster-loading web pages: WebP is typically 25–35% smaller than BMP while keeping both quality and transparency. It is perfect for website images; if your audience uses older software without WebP support, use JPG or PNG instead.
BMP vs WebP: key differences
| Property | BMP | WebP |
|---|---|---|
| Compression | Lossless | Lossy |
| Transparency | No | Yes |
| Best for | Raw, uncompressed Windows bitmaps | Fast-loading website images |
Modernising old BMP assets into lean WebP files
If you're sitting on a pile of ancient BMP assets and want to reuse them on a current website, dropping them in as-is is painfully heavy. Converting to WebP is the smartest move today: at the same visual quality the files are usually smaller than JPG, and WebP keeps transparency, so a cut-out logo or icon stays clean and pages load faster.
The catch is compatibility. Every modern browser handles WebP fine, but very old image viewers, legacy operating systems and some corporate tools simply can't open it. If the image is going to someone whose setup you can't predict, or into an aging workflow, play it safe and fall back to JPG or PNG.
Why -99% and not -100%
It is rounding, and the rounding itself tells you how wide the gap is. The screenshot goes from 2.75 MB to 7.3 KB and the illustration to 10.2 KB — both shed more than 99.7%. The table prints -99% rather than rounding up to -100%, because "-100%" would read as the file becoming nothing, and that cannot happen. The photo is the only row that never runs into that ceiling: 303.1 KB (-89%). Why the spread is so wide: a BMP's size is decided purely by dimensions, while a WebP's size is decided by how predictable the content is. An interface graphic made mostly of flat colour compresses almost to nothing; a photograph full of grain does not. So the size drop here is not a credit to the tool — it is a measure of how much the original format was wasting. What does deserve attention is elsewhere: WebP is unsupported before Safari 14, and if you want lossless archival, PNG is the right exit.