BMP to JPG

BMP is essentially a raw pixel dump with a header. It applies no meaningful compression at all, which makes BMP files far larger than any modern format — and makes this one of the most dramatic size reductions available.

How much larger BMP really is

A 1600×1000 image stored as 24-bit BMP takes about 4.8 megabytes regardless of what it depicts, because every pixel costs three bytes and nothing is compressed. In our own test set, an image that is 46 KB as an optimised PNG occupies 6.4 MB as a BMP — roughly 140 times larger.

That ratio holds for simple graphics. For photographs the gap narrows in relative terms but the absolute file sizes get much worse, because BMP scales purely with pixel count.

Where BMP files still come from

Older Windows software, scanner drivers, medical and industrial imaging tools, some CAD exports, and the classic Windows Paint save dialogue all still produce BMP. It survives because it is trivially simple to read and write, which matters for embedded and legacy systems.

It is a reasonable working format inside such a system and a poor one for sending anywhere. Email attachments, upload forms and web pages all struggle with multi-megabyte uncompressed images.

Choosing JPG or PNG as the target

If the BMP is a photograph or a scan, JPG is the right answer and the reduction will be enormous. At quality 85 the visible difference is negligible relative to the space saved.

If the BMP is a screenshot, a diagram or line art, JPG is the wrong target — it will produce ringing around sharp edges and may not even be smaller. Convert those to PNG instead, where lossless optimisation typically gives a very small file with perfectly crisp edges.

No upload, which matters more here

BMP files are big, so uploading them to a conversion service is slow and wasteful. Breezo reads the file with your browser's native decoder and encodes JPEG with MozJPEG compiled to WebAssembly, all locally.

A large BMP never has to cross the network at all, and there is no file size cap to run into.