How to convert BMP to PNG
- Drop in your bitmaps. Other supported image formats can go in the same batch — you do not have to sort files by format first.
- Tick the ones you want in this round. Everything you add starts selected; untick anything you want to skip.
- Leave Export as on PNG. PNG has nothing to configure.
- Press Export. A single file downloads directly; two or more arrive as one ZIP.
Your files stay in the workspace after an export, so you can change the selection or the output format and export again without adding anything twice.
Why BMP files are so large
A BMP usually stores every pixel as raw bytes with little or no compression. That is exactly why the format survived in Windows tooling for so long — it is trivial to read and write — and also why a screenshot saved as BMP can be tens of megabytes when the same picture as PNG is a fraction of that.
PNG stores the same pixels, but it compresses them. Nothing is discarded and nothing is approximated: decode the PNG and you get the bitmap back. For screenshots, diagrams, UI assets and anything with flat areas of colour, the saving is usually large. For noisy photographic content it is smaller. We are deliberately not printing a percentage here, because the honest answer depends entirely on the picture.
Where BMP files still come from
- Older Windows software — scanners, point-of-sale systems, lab and industrial tools and legacy line-of-business apps still export BMP because it is the simplest thing to write.
- Screenshots and exported bitmaps from utilities that offer BMP as the default.
- Game and application assets from older toolchains, where BMP was the working format.
- Anything you now need to put on the web or in a document — browsers, chat apps and document editors all handle PNG everywhere; BMP support is patchy and the files are needlessly heavy.
What this page supports
- Input: BMP — plus JPG, PNG, WebP and AVIF if you want to mix them into the same batch.
- Output: PNG by default; JPG and WebP are one dropdown away. BMP itself cannot be exported here — it is a format this page reads, not one it writes.
- Transparency: most BMP files have no transparency at all. If the bitmap your browser decodes does carry usable alpha — 32-bit BMPs with an alpha mask can — PNG will preserve it. If it does not, there is nothing to preserve and nothing is invented.
- What lossless means here: the pixels your browser decoded out of the BMP are stored exactly. PNG has no quality dial, so there is nothing to set and nothing to get wrong.
- Metadata: EXIF, ICC colour profiles and capture dates are not carried over. Keep the original file if you need them.
- Batch: files are processed one at a time so memory stays predictable; duplicate output names are numbered automatically.
- Size: no fixed limit is imposed. The practical ceiling is your device's memory.
Decoding a BMP is something your browser does. BMP is an old family with many header variants, and a browser that cannot read a particular one will mark that file as failed — the rest of the batch still converts. One file that cannot be read never stops the others.
Questions
Are my images uploaded?
No. Everything happens inside your browser tab: files are read from disk into memory, redrawn, and re-encoded locally. Nothing is sent to a server, so there is no server-side copy to delete afterwards. You can keep the network panel open while you convert — it stays quiet.
Will the PNG lose any quality?
No. PNG is a lossless format: it stores the decoded pixels exactly and there is no quality setting to get wrong. Converting BMP to PNG changes how the pixels are packed, not what they are.
How much smaller will the file get?
It depends on the picture, and we would rather not quote a number we cannot stand behind. Screenshots, diagrams and anything with large flat areas usually shrink a lot, because that is what PNG compression is good at. Photographic, noisy images shrink less. Either way, no detail is given up to get there.
Is transparency kept?
If there is any. Most BMP variants have no alpha channel at all, so there is simply nothing to keep. Some 32-bit BMPs do carry an alpha mask, and when your browser decodes one of those, the transparent areas stay transparent in the PNG.
Can I convert a PNG back to BMP here?
No. This page reads BMP and writes PNG, JPG or WebP. There is no BMP output — BMP is a format we can open, not one we produce.
Can I convert a whole folder at once?
Yes. Add as many files as you like, tick the ones you want in this round, and export — one file downloads directly, two or more arrive as a single ZIP. The files stay in the workspace afterwards, so you can export a different selection or a different format without re-adding them.