BMP to JPG Converter - Convert BMP to JPG Free Online

What BMP to JPG Does

This tool decodes your BMP onto an in-browser canvas and re-encodes the pixel data with the browser's own JPG encoder. The size difference between the two files is the whole point, and it comes entirely from how each format stores pixels. A BMP, in nearly every common variant, is uncompressed: the file holds the raw bytes of every pixel in sequence, row by row, behind a small header. A 1920x1080 image at 24 bits per pixel therefore costs around 6 MB regardless of what it depicts — a detailed photograph and a flat grey rectangle occupy the same space. JPG works the opposite way. It converts the image into frequency components, discards the ones the eye is least likely to notice, and entropy-codes what is left, so that same 1920x1080 photo usually lands in the low hundreds of kilobytes. The saving is real, but it is achieved by throwing data away rather than packing it more cleverly. Two things follow from that. First, the conversion is one-way: BMP is lossless, so every pixel in it is original, and once the JPG encoder has run, the detail it dropped is gone for good. The Quality slider, running 1 to 100 with a default of 92, controls how much gets dropped. Second, 32-bit BMP files can carry an alpha channel and JPG cannot store transparency at all, so transparent pixels are composited onto white before encoding. What the tool does not change is the image itself — output width and height match the input exactly.