What a BMP file contains
A BMP file holds a small header describing the dimensions and color depth, followed by the pixel grid. Many variants write every pixel at full size so a program can read the image straight into memory.
Some BMP variants allow basic compression, but the common ones do not. A 1,920 by 1,080 image with 24-bit color can therefore take up several megabytes with no quality benefit over a smaller lossless file.
Why BMP files are so large
Because pixels are stored directly, there is little redundancy left for a compressor to exploit. The advantage is speed and simplicity: decoding a BMP takes very little work and never changes the image.
That trade made BMP useful for icons, splash screens, and captures inside Windows applications, but it is a poor fit for web pages, email, or any service with an upload limit.
- Raw pixels with little compression
- Large files even for modest dimensions
- Common in older Windows software and drivers
- Poor choice for web and mobile delivery
Converting away from BMP
PNG is the natural replacement when you need identical pixels, while JPEG or WebP gives a much smaller photograph. Converting only changes the container; the visible detail is whatever the BMP already held.
Filekind does not convert BMP today. Its converter accepts JPEG, PNG, and static WebP, so a BMP must first be exported as one of those formats by other software.