Convert BMP to PNG
Drop a BMP file below and get a PNG back. The conversion happens on your own machine, so nothing is uploaded and there is no size or quantity limit beyond what your browser can hold in memory.
Drop images here
Ctrl/⌘ VPaste a screenshot or copied image
Accepts BMP
Lower means a smaller file. 75 is a good default for photos.
100% in your browser Files are never uploaded.
Why convert BMP to PNG?
Plenty of websites, content management systems and older desktop programs reject BMP uploads outright. PNG is accepted just about everywhere, and that alone accounts for most of these conversions.
For the same picture, PNG usually lands well under the size of the BMP original. That matters when you are trimming page weight or squeezing under an upload limit.
PNG supports an alpha channel, so you can cut out a background after converting. The conversion itself will not invent transparency that the BMP file never had.
PNG is lossless, so the conversion adds no new compression artefacts. Whatever detail survives in the BMP file is carried across exactly.
PNG is the format most image editors and design tools expect, which makes it the practical choice when the file is headed for further editing rather than straight onto a web page.
This is the most straightforward upgrade in image formats. Both are lossless, so nothing about the picture changes at all — every pixel arrives exactly as it left. The only difference is that PNG actually compresses, while BMP essentially does not. There is no trade-off to weigh here, which makes it unusual on this site.
Before you convert
Identical picture, a fraction of the size
An uncompressed BMP spends the same three bytes per pixel whether the image is a photograph or a solid white rectangle. PNG applies real lossless compression, and on the flat-colour and repetitive content BMP files usually hold — screenshots, scans of documents, exports from older software — the reduction is often to a tenth or less of the original. Photographic content compresses less well, but still meaningfully.
Nothing is lost, so nothing needs deciding
There is no quality setting to weigh, no artefacts to look out for and no one-way door. If you ever need the BMP back, converting in the other direction reproduces it exactly. For archiving old material this makes PNG a safe destination — you are only changing how the data is packed, never the data itself.
If the BMP holds a photograph, consider going further
PNG is the right answer for graphics and for anything you intend to keep editing. For a photograph that just needs to be sent or displayed, a lossy format will be an order of magnitude smaller again with no visible difference — JPEG for maximum compatibility, WebP or AVIF if the destination is a web page. PNG's losslessness is valuable, but it is worth paying for only when you actually need it.
What carries over
- Every pixel, exactly
- Transparency, if the BMP had it
- The ability to convert back unchanged
What does not
- A large majority of the file size
- Nothing about the image itself
BMP vs PNG at a glance
| Property | BMP | PNG |
|---|---|---|
| Compression | Lossless | Lossless |
| Transparency | No | Yes |
| Typical file size | 800-1200% of an equivalent JPEG | 300-500% of an equivalent JPEG |
| Compatibility | Supported by all current browsers and most apps | Opens everywhere, including decades-old software |
| Usually comes from | Older Windows software and scanners | Screenshots, logos and graphics |
Frequently asked questions
Are my BMP files uploaded anywhere?
No. The decoder and encoder are WebAssembly modules that run inside this page. The network tab may show a codec downloading the first time you use a format, but no request contains your file. On supported browsers, a codec that has already been used is cached so the same conversion can work offline.
Is there a file size or quantity limit?
There is no limit imposed by us. The practical ceiling is your device’s memory, since the image has to be held uncompressed while converting. On a typical laptop, images up to around 100 megapixels convert without trouble.
Will converting to PNG lose quality?
PNG is lossless, so every pixel is preserved exactly. The file will usually be larger than the original, which is the trade-off for keeping all the data.
Does it work on a phone?
Yes. The same WebAssembly modules run on mobile browsers. Conversion is slower than on a desktop because phone CPUs are weaker, and very large images are more likely to hit memory limits.
Why is my BMP file so large?
BMP stores pixels essentially uncompressed, so a single photograph can run to tens of megabytes. That alone usually makes the conversion worthwhile — expect the PNG file to be a small fraction of the original with no visible difference.
Why is the PNG bigger than the original?
PNG is lossless, so it stores every pixel exactly instead of approximating them. For photographs that usually means a file several times larger than a lossy original. PNG earns its keep with screenshots, logos, line art and anything needing transparency — not with photos.