Sending BMP screenshots by email or chat when the identical PNG would be a small fraction of the size.
File formats
BMP
Also called .bmp, bitmap or windows bitmap. Here is what it means, when it changes what you export, and what people get wrong.
File formatsRuns on your deviceUpdated 10 August 2026
The short answer
BMP is Microsoft's raster image format, which stores each pixel's colour value directly with little or no compression. That makes files very large while offering no quality advantage over PNG, which is also lossless but far smaller. Little produced today needs BMP outside legacy Windows software.
Updated
The short version
BMP at a glance
| Quick fact | Detail |
|---|---|
| Also known as | DIB, device-independent bitmap |
| Compression | Usually none; optional RLE is rare |
| Bit depth | 1, 4, 8, 16, 24 or 32 bits per pixel |
| Transparency | Only in later header versions, unevenly supported |
| Metadata | No EXIF, minimal beyond the header |
| Modern replacement | PNG, lossless and much smaller |
Slide the table sideways to see every column.
Why are BMP files so large?
Because the size is arithmetic rather than compression. A standard 24-bit BMP spends three bytes on every pixel, plus padding to round each row up to a multiple of four bytes, plus a small header. A 1920 x 1080 screenshot therefore costs about 6 MB before anything else happens. The same screenshot as a PNG, with its flat interface colours and repeated edges, often lands under 200 KB.
The format does define optional run-length encoding for 4-bit and 8-bit images, but it is rarely used and only helps on flat graphics. In practice a BMP is a raw pixel dump with a header on the front.
Is there any reason to still use BMP?
Two narrow ones. It remains part of Windows internals, where device-independent bitmaps back the clipboard, icon and cursor resources, and older GDI drawing code. And it is trivial to read and write, which occasionally matters in embedded work or in a program that cannot afford a compression library.
For anything else, PNG replaces it exactly: also lossless, also pixel-for-pixel identical to the original, with real transparency and a fraction of the size. If you have a folder of BMP files, converting them to PNG loses nothing at all.
What people get wrong about bmp
Each one is a real failure mode, not a style preference.
Assuming a BMP holds more quality than a PNG because the file is bigger; both store the exact same pixels.
Relying on the alpha channel in a 32-bit BMP, which many readers ignore and render as opaque.
Questions people ask
BMP, answered
The follow-up questions people search for once they have the definition.
Is BMP higher quality than PNG?
No. Both are lossless, so a BMP and a PNG made from the same source contain identical pixels. The BMP is simply larger because it does not compress. File size and image quality are not the same thing.
Does BMP support transparent backgrounds?
In theory, through 32-bit variants defined by the later header versions. In practice support is inconsistent and many applications treat the fourth channel as unused, showing the image as fully opaque. Use PNG when transparency needs to survive.
Should I convert my BMP files to PNG?
Yes, in almost every case. PNG is lossless, so the conversion changes no pixel values, and the result is usually far smaller with better metadata and transparency support. Keep BMP only where a specific piece of legacy software demands it.
Same cluster
More from the glossary
Neighbouring entries, so every term in the set is one hop from every other.
Bokeh
Bokeh is the character of the out-of-focus parts of a photo, not simply how much blur there is.
Checkerboard pattern
The grey and white checkerboard behind an image is not part of the picture.
Bicubic interpolation
Bicubic interpolation works out each new pixel by fitting a smooth cubic curve through a 4 x 4 block of sixteen surrounding pixels.
From the studio
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Sources
Where the facts on this page come from. Every link opens the specification, standard or documentation the claim was read at.
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