BMP (Windows Bitmap)
BMP is Microsoft’s raw, uncompressed bitmap format — every pixel stored literally, with no compression at all.
- File extension
- .bmp, .dib
- MIME type
- image/bmp
- Compression
- Lossless
- Transparency
- No
- Animation
- No
- Type
- Raster (pixels)
Where BMP files come from
Legacy Windows applications, scanners, and industrial equipment.
Strong on Windows, weak everywhere else, and never used online.
What BMP is good at
- Dead simple and completely lossless
- Read by even the most primitive Windows tooling and embedded devices
- No decoding overhead, which some industrial and medical systems require
Where BMP falls short
- Enormous files — often 10–20x larger than a PNG of the same image
- Poorly supported on the web; browsers can display it but nobody serves it
- No transparency in the widely supported 24-bit form, so transparent areas are filled with a solid colour
Should you use BMP?
Use it when the image must survive editing and re-saving without degrading, or when transparency matters. Avoid it for large photographs that only need to be viewed, where a lossy format will be a fraction of the size with no visible difference.
Convert from BMP
Convert to BMP
Frequently asked questions
What is BMP (Windows Bitmap)?
BMP is Microsoft’s raw, uncompressed bitmap format — every pixel stored literally, with no compression at all. Strong on Windows, weak everywhere else, and never used online.
How do I open BMP files?
Any tool that lists BMP support will open one. If yours will not, the quickest fix is to convert it to a format your software already understands — the converters linked on this page do that in your browser without uploading the file.
Is BMP lossy or lossless?
BMP is lossless — every pixel is stored exactly, and re-saving it repeatedly costs you nothing in quality. The trade-off is a larger file.
Does BMP support transparency?
No. BMP has no alpha channel, so transparent areas must be filled with a background colour when you convert into it. White is the usual choice.