About BMP Files

BMP Image

Released 1985 By Microsoft & IBM (OS/2 + Windows 1.0)

BMP is an uncompressed raster image format native to Windows. Files are large but preserve exact pixel data with no compression artifacts. Rarely used on the web due to file size.

Family

Raster & Vector Images

Extension

.bmp

MIME Type

image/bmp, image/x-ms-bmp

Can Use As

Input Output

The story

HOW BMP
CAME TO BE.

BMP — short for Bitmap — is one of the oldest image formats still in everyday use. It shipped with Windows 1.0 in 1985 and with OS/2 shortly after. The design philosophy was "store pixels as pixels": no compression, no tricks, just a header describing dimensions and color depth followed by raw pixel data. That simplicity made it trivial for any Windows program to read or write a BMP in a few dozen lines of code.

For a while, BMP was everywhere. Windows wallpapers, clip art CD-ROMs, print-shop templates. Then JPEG and PNG arrived and BMP slowly retreated to technical niches: embedded systems with limited CPU, legacy Windows APIs, and educational programming exercises ("write a BMP parser" is still a CS101 assignment). Today .bmp is mostly a compatibility fallback, but its straightforwardness is why it refuses to die.

CURIOSITIES &
TRIVIA.

A blank 4K BMP file takes up about 25 MB — the same image as PNG is typically under 100 KB.

BMP pixel rows are padded to 4-byte boundaries, which confuses anyone writing their first parser.

The format stores pixels bottom-to-top by default, the opposite of most modern formats.

Windows has updated the BMP header 6 times (BITMAPCOREHEADER through BITMAPV5HEADER) — a readable file might use any of them.

MS Paint defaulted to saving as BMP until Windows 7 quietly switched it to PNG in 2009.

STRENGTHS &
LIMITATIONS.

Strengths

Dead-simple format — trivially easy to read and write.
Lossless and uncompressed — perfect bit-exact pixel storage.
Universally supported in Windows applications since 1985.
Supports 1, 4, 8, 16, 24, and 32-bit color depths.

Limitations

Enormous file sizes — no meaningful compression in typical use.
Not a web format — browsers support it but nobody serves BMPs over HTTP.
No metadata support (no EXIF, no ICC profile in practice).
Multiple header versions mean "a BMP" is ambiguous — parsers must handle several variants.

Typical Sizes & Weights

Small icon (32×32)

4 KB

Screenshot (1920×1080)

~6 MB

4K image (3840×2160)

~25 MB

Scanned A4 at 300 dpi

~25 MB

Technical Specifications

MIME type: image/bmp
Extensions: .bmp, .dib
Compression: None (typical); RLE 4/8 bit (rare)
Color depths: 1, 4, 8, 16, 24, 32 bits per pixel
Byte order: Little-endian

CONVERT FROM
BMP

bmp jpg bmp png bmp webp bmp avif bmp gif bmp tiff bmp ico bmp svg bmp psd bmp eps bmp pdf bmp tga bmp exr bmp pcx bmp sgi bmp dpx bmp pnm bmp xbm bmp xpm bmp wbmp bmp miff

CONVERT TO
BMP

jpg bmp jpeg bmp png bmp webp bmp avif bmp gif bmp tiff bmp ico bmp svg bmp heic bmp heif bmp psd bmp jxl bmp jp2 bmp eps bmp dng bmp jfif bmp pgm bmp ppm bmp pbm bmp tga bmp exr bmp hdr bmp xcf bmp emf bmp wmf bmp cr2 bmp nef bmp arw bmp orf bmp rw2 bmp cr3 bmp raf bmp sr2 bmp pef bmp icns bmp svgz bmp dds bmp pcx bmp sgi bmp dpx bmp pnm bmp xbm bmp xpm bmp fits bmp wbmp bmp cin bmp miff bmp raw bmp ai bmp indd bmp cdr bmp mp4 bmp mov bmp mkv bmp avi bmp webm bmp flv bmp wmv bmp mpeg bmp 3gp bmp ogv bmp vob bmp m4v bmp ts bmp m2ts bmp mts bmp swf bmp mpg bmp asf bmp dv bmp f4v bmp h264 bmp h265 bmp m2v bmp mjpeg bmp mxf bmp rm bmp rmvb bmp divx bmp nut bmp y4m bmp doc bmp docx bmp odt bmp rtf bmp xls bmp xlsx bmp ods bmp ppt bmp pptx bmp odp bmp pdf bmp

Common Use Cases

Windows system graphics, legacy applications, lossless image storage.