Convert BMP to PNG
Free online converter for BMP files. Lossless raster format with alpha transparency. Nothing to install, no watermark, and every file is deleted automatically.
Drag and drop your files
or
Upload a BMP file to convert it to PNG. Up to 3 files at once, 100 MB each.
Free · up to 3 files · 100 MB each · files deleted automatically after 1 hour.
About BMP and PNG
BMP .bmp
Microsoft's plain bitmap. It generally stores pixels with no compression at all, which makes it simple to read and very large on disk.
Good for
- Dead simple — every pixel stored literally
- No compression artefacts of any kind
- Reliably readable by old Windows software
Trade-offs
- Enormous files, often ten times a PNG of the same image
- Effectively unusable on the web
- Transparency support is inconsistent between readers
image/bmp
PNG .png
A lossless image format built for graphics rather than photographs. Every pixel it stores comes back exactly as it went in, and it carries a full alpha channel for transparency.
Good for
- Lossless — no generation loss no matter how often you re-save
- Full 8-bit alpha, so edges blend cleanly over any background
- Sharp on text, screenshots, logos and line art
Trade-offs
- Much larger than JPEG for photographs
- No animation in the baseline format
- Large photographic PNGs are slow to transfer
image/png
BMP and PNG side by side
| BMP | PNG | |
|---|---|---|
| Compression | Uncompressed | Lossless |
| Transparency | Limited — 32-bit variants only | Yes — 8-bit alpha |
| Animation | No | No |
| Typically used for | Legacy Windows software, intermediate working files | Screenshots, logos, UI assets, anything with transparency |
What changes when you convert BMP to PNG
How the PNG is written
Our default is maximum compression with adaptive filtering, and fully lossless — lowering the quality dial is what switches PNG to a 256-colour palette, and it is at 100 unless you move it. The quality control on the converter moves this if you need to — the default aims to be indistinguishable from the source at a sensible file size, rather than to win a compression benchmark.
Expect a dramatic drop in size
A BMP stores every pixel literally, with no compression at all — which is why they are so large. PNG compresses, so the same image commonly lands somewhere between a tenth and a half of the size it started at. Nothing about the picture changes to achieve that: the file was simply storing its pixels in the least efficient way available.
Nothing is lost in this step
Both BMP and PNG store every pixel exactly, so this conversion changes the container rather than the content. What changes is file size and what will open it — convert freely, and as often as you like, without degrading anything.
Other BMP conversions
Other ways to get PNG
Worth reading next
Why your PNG is so much bigger than your JPEG
The same photograph can be 300 KB as a JPEG and 4 MB as a PNG. Here is what each format is actually doing, and how to tell which one your file wants to be.
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Where your transparent background went
Transparency is the property most often lost silently in a conversion — the file looks perfect until it lands on a coloured background and grows a white rectangle.
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