Not every oversized BMP deserves lossy compression. Pixel art, sprites pulled from old games, interface screenshots, engineering diagrams, and captures from technical software all share one trait: they are full of sharp edges and flat color, and pushing them through JPEG would visibly damage exactly the details that matter. What these files need is a format that shrinks them without touching a single pixel — which is precisely what PNG was designed to do.
BMP and PNG both store images losslessly; the difference is that BMP typically writes the pixel data raw, while PNG runs it through real compression before saving. The result is a file that decodes to the identical image but often occupies a small fraction of the space, especially for the flat-color, hard-edged content BMPs so often contain. PNG also opens natively everywhere — browsers, documents, chat apps, content-management systems — while BMP support outside Windows is inconsistent at best. A BMP attached to an email or dropped into a web page is a gamble; a PNG simply works.
Convertmaxxing keeps the entire process on your machine. Drop the BMP onto the page and it is decoded and re-encoded right there in the browser tab via WebAssembly; the file is never uploaded, no signup stands in the way, and after the engine's one-time download of about 5 MB your browser caches it, so later conversions start instantly. It costs nothing, and if you want the output scrubbed of metadata there is an option for that — though BMPs rarely carry much metadata to begin with, so there is usually little to remove.
There are also no settings to agonize over, because there is nothing to trade away. This conversion has no quality dial — lossless in means lossless out — so the PNG you download contains exactly the pixels you fed in, just packed far more efficiently. That makes it a safe default for archiving old bitmaps too: you reclaim disk space without wondering, years later, whether the compression quietly cost you anything.
Why convert BMP to PNG?
- PNG stores the identical image losslessly, often at a small fraction of the BMP's size
- Sharp text, pixel art, and diagrams keep every edge crisp — no compression artifacts, ever
- PNG opens everywhere, while BMP support outside Windows is unreliable
- The conversion runs entirely on your device — free, no account, no upload
How it works
- Step 1
Drop your files
Drag your BMP files into the converter above, or click “Choose files”. Batches are welcome.
- Step 2
Pick your settings
PNG is preselected. Adjust quality or size if you want, or keep the defaults.
- Step 3
Convert and download
Conversion runs locally in your browser. Download files individually or grab everything as a zip.
Frequently asked questions
- Is BMP to PNG conversion really lossless?
- Yes, in the strictest sense. PNG compression is fully reversible, so the converted file decodes to the same pixels as the original BMP — not visually similar, but identical. You can convert, delete the bulky BMP, and lose nothing.
- How can the PNG be smaller if nothing is thrown away?
- The same way a zip archive shrinks a document without deleting words. PNG finds repetition and patterns in the pixel data and encodes them compactly, then reverses the process perfectly when the image is opened. Since BMPs are usually stored with no compression at all, and since screenshots and graphics are full of repeated flat color, the savings are often dramatic.
- Where does the conversion actually happen — on my computer or yours?
- Entirely on yours. The converter is WebAssembly code running inside your browser, so the BMP is opened, converted, and saved without ever crossing the network. No server receives your file, and nothing is stored anywhere else — the only download involved is the conversion engine itself, which your browser caches after the first use.
- What about transparency — will my PNG have any?
- The conversion preserves what is in the source, and nearly all BMPs are fully opaque, so the resulting PNG will typically be opaque too. The difference is that PNG fully supports alpha transparency going forward: once the image is in PNG form, you can open it in any editor and knock out a background, which BMP handles poorly.
- Why is there no quality slider for this conversion?
- Because there is no quality decision to make. A quality slider only makes sense for lossy formats, where you trade fidelity for size. PNG is lossless — the output always contains the complete, exact image — so the converter has nothing to ask you and simply produces the smallest faithful file it can.