Converting BMP to WebM gives you a much smaller file, with transparency filled in. It runs in your browser: nothing is uploaded, there is no queue and no size limit.
What changes when you convert BMP to WebM
- BMP is lossless and WebM is not. Expect a much smaller file and a very small, usually invisible, loss of detail. Keep the BMP if you may edit again.
- WebM has no transparency. Transparent areas are filled with a background colour (white by default, though you can pick another).
When to convert, and when not to
Convert to WebM for video embedded in web pages. Open VP9/Opus format built for the web. Smaller than MP4 at equal quality.
Keep BMP for legacy Windows software. Uncompressed Windows bitmap. Huge files, trivially simple.
How to convert BMP to WebM
- Drop your BMP file on the converter above, or click to choose. Several at once is fine.
- Check the options if you need them: video quality.
- Click Convert, then Download. Nothing was sent anywhere, your browser did the work.
Questions
Is my BMP file uploaded?
No. The conversion runs in your browser with WebAssembly. There is no upload endpoint on this site. You can open your browser's Network tab, or go offline after the page loads, and it still works.
Is there a file size limit?
No fixed one. The limit is your device's memory: a large images file on a phone is slower than on a laptop, but nothing is rejected for being big.
Is it free?
Yes, without an account, without a daily cap and without a watermark. Your device does the computing, so there is no server bill to pass on.
Will the quality drop?
WebM is lossy, so a little detail is traded for a smaller file. At quality 85 the difference is invisible on photos. For graphics with sharp edges, prefer a lossless format such as PNG.
Can I convert several files at once?
Yes. Drop them all; each is converted in turn and you can download them one by one or as a single ZIP.
Which engine does the conversion?
Media engine (FFmpeg, multithreaded WebAssembly), compiled to WebAssembly and running in your browser, on all your CPU cores when the browser allows it. First use downloads about 31 MB, cached afterwards.