Where BMP files come from
BMP is the classic Windows bitmap format. It still turns up in many places: older versions of Paint, some scanners and scanning software, industrial and medical equipment, point-of-sale systems, old games and programs that export screenshots, and folders of pictures copied from computers that are twenty years old. If you've received a BMP from one of these sources, you've probably noticed two things: it's huge, and many websites won't accept it.
BMP usually stores every pixel with little or no compression. A single picture can weigh several megabytes, which is too much for an email attachment limit, a job portal, a school platform or a messaging app. Most upload forms also list only JPG, PNG or PDF, so a BMP gets rejected even when it's small.
Why JPG is the usual answer
JPG is accepted practically everywhere and compresses photos very efficiently. Converting a BMP photo or scan to JPG normally makes it much lighter while it still looks the same on screen. That makes it the right choice for photos, scanned documents you need to send, and pictures you want to share from an old computer.
If the BMP is a screenshot, a diagram or a graphic with small text and sharp lines, consider “BMP to PNG” instead. PNG is lossless, so thin lines and letters stay perfectly crisp, while a JPG at low quality can show soft edges around them.
Quality and size
The quality setting decides the balance between detail and file size. For photos, a high or medium quality is usually indistinguishable from the original BMP on screen. For scans of documents with text, keep the quality high so the letters stay sharp.
If a portal also sets a limit in KB or MB, send the JPG to “Compress image” afterward and type the target size. If it needs exact pixel dimensions, “Resize image” does that. You don't need to select the file again for either step.
No uploads, no account
The conversion runs in your browser: your BMP files are never uploaded to a server or stored anywhere. That matters when the files are scans of personal documents or pictures from work equipment. There's no sign-up, no watermark and no limit on how many files you convert, and you can process a whole batch and download the results together in a ZIP.
Need a document rather than images? Send the JPG files to “JPG to PDF”, or use “BMP to PDF” directly to put your bitmaps into one PDF.