BMP is an old, uncompressed image format from Windows. Because it stores every pixel as is, BMP files are very large and many websites, apps and upload forms refuse them. Converting BMP to WebP gives you small files that still support transparency.
WebP gives small files with good quality and supports transparency, which is why many websites use it for photos and graphics. WebP is lossy at lower quality settings, and a few older apps and programs still cannot open it, so check the destination first. BMP files rarely carry transparency, so the result looks the same as the original. Converting removes the bulk, and a BMP often shrinks to a small fraction of its size.
Choose High for a good balance, Max for the least visible loss, or Low when file size matters most. The pixel dimensions follow the original, each file keeps its name with only the extension swapped, and no metadata or watermark is added. Everything runs in your browser, so your images are never uploaded.
Tip: Screenshots and scans saved as BMP are the usual candidates. PNG is the safe pick for them, and WebP makes them smaller still.
Slightly. WebP is a lossy format, so some fine detail is discarded. At High quality the difference is hard to see in photographs. Text and sharp line art show it more easily.
Most BMP files have no transparency. The few that do keep it when you convert to PNG or WebP, and get a white background in JPG.
BMP stores raw, uncompressed pixel data. A format with compression, such as PNG, JPG or WebP, saves the same picture in a fraction of the space.
Yes. Add them all, convert once and download a single ZIP. Only the extension changes. A file named scan.bmp becomes scan.webp.
No. The conversion happens in your browser and the files never leave your device.