What bit depth are the BMP samples?

24-bit RGB with no compression and no colour table.

What is the MIME type of a BMP file?

The MIME type is image/bmp. The file extension is .bmp.

Is a sample BMP file the same as a dummy or example BMP file?

Yes. Sample, test, dummy and example BMP files are different names for the same thing: a BMP file with known contents that stands in for a real one. Any file on this page will do wherever a tutorial or a test plan asks for a dummy BMP file.

Free BMP sample files

Uncompressed bitmap images. Large, simple and useful for testing how software handles inefficient formats. Download valid BMP test files in 4 exact sizes, from 10 KB to 5 MB, each with a checksum.

Extension: .bmp
MIME type: image/bmp
Kind: Binary
Category: Images

BMP files by size

Every file below is a valid Windows bitmap file of exactly the stated size. Open a file's page for its checksum and contents, and to preview it in your browser before downloading.

BMP sample files by size
File	Size	Contents	Download
10 KB BMP samplesample-bmp-10kb.bmp	10 KB10,240 bytes	67 × 49 px	Download BMP
100 KB BMP samplesample-bmp-100kb.bmp	100 KB102,400 bytes	213 × 159 px	Download BMP
1 MB BMP samplesample-bmp-1mb.bmp	1 MB1,048,576 bytes	683 × 510 px	Download BMP
5 MB BMP samplesample-bmp-5mb.bmp	5 MB5,242,880 bytes	1,526 × 1,144 px	Download BMP

What is a BMP file?

BMP stores pixels almost exactly as they sit in memory, usually without compression. A header describes the dimensions and bit depth, and the rows of pixels follow, normally from the bottom of the image upward.

Because there is no compression, file size is simply width × height × bytes per pixel plus a small header.

How to recognise a BMP file

42B4DM

The first bytes of every file.

Extension	.bmp
MIME type	image/bmp
Header	BITMAPFILEHEADER and a DIB header
Compression	Usually none
Row order	Bottom-up by default
Row padding	Each row is padded to a multiple of four bytes

What to test for

These are the behaviours that most often go wrong when software handles BMP files.

Row padding and bottom-up order are the usual causes of skewed or upside-down images in hand-written decoders.
Some validators accept BMP by MIME type but have no decoder for it, which fails later in the pipeline.

Strengths of BMP

Trivial to read and write without a library.
No compression, so no quality loss and no decoding cost.

Limitations of BMP

Enormous files: every pixel is stored in full.
Unsuitable for the web, and rarely accepted by upload forms.

Typical uses of BMP test files

Testing size limits with naturally large images
Checking that services convert BMP to a web format
Testing decoders for legacy formats

Software that opens BMP

Windows Paint and Photos
All major browsers
Image editors and Pillow, ImageMagick

Specifications

Microsoft: Bitmap Storage

BMP sample files: questions

What bit depth are the BMP samples?: 24-bit RGB with no compression and no colour table.
What is the MIME type of a BMP file?: The MIME type is image/bmp. The file extension is .bmp.
Is a sample BMP file the same as a dummy or example BMP file?: Yes. Sample, test, dummy and example BMP files are different names for the same thing: a BMP file with known contents that stands in for a real one. Any file on this page will do wherever a tutorial or a test plan asks for a dummy BMP file.