Questions about BMP and WebP
Why are BMP files so absurdly large?
There is no compression in the format. Three bytes per pixel, multiplied by every pixel, plus a small header. That was a reasonable design in 1990 when the alternative was slow decoding; today it means a folder of BMPs will fill a disk that could hold a hundred times as many WebPs.
Where do BMP files even come from?
Scanners, industrial and medical equipment, older Windows software, and screen-capture tools that never updated their defaults. They are rare on the web precisely because nobody wants to send 36 MB down a wire.
Will I lose anything converting?
Technically yes — WebP is lossy at these settings while BMP is not. Visually, at a sensible target size, no. If the source is a scan you need pixel-exact for archival or legal reasons, keep the original and publish the WebP.
Are my images really not uploaded?
Correct. The conversion uses your browser's own image engine, so the file is read from your disk into the tab and never sent over the network. Open your browser's network panel and convert something — no request is made.
How does the target size work?
The converter encodes your image, checks the result against your target, and adjusts quality until it fits. If quality alone cannot get there, it reduces the dimensions in steps rather than destroying the picture. You always see what happened.
Is there a limit on how many files I can convert?
None from us — your computer does the work, not our server. The practical ceiling is around 40 megapixels per image, where browsers stop being reliable.