Convert BMP to JPG

How to use it#

1. Drop your BMP files onto the box above, or click it to pick them.
2. Move the quality slider if you want a smaller file or a sharper picture.
3. Download each JPG, or take them all at once.

Why BMP files are so large#

BMP is the bitmap format from early Windows, and in most files every pixel is stored as it is, with no compression at all. A 1920 by 1080 screenshot takes about 6 MB as a BMP whatever is in it. The same picture as a JPG is usually a few hundred kilobytes.

That is why a BMP is rejected by upload limits, bounces from email, and fills a folder quickly. Converting BMP to JPG (the same format some programs call JPEG) is often all it takes to get the file where it needs to go.

When a PNG would be better#

JPEG discards detail the eye is unlikely to notice in a photograph, and that suits a scanned photo or a camera picture saved as BMP. It suits screenshots, diagrams, and text less well, where it leaves faint smudges around sharp edges.

For those, a lossless PNG keeps every pixel and is still far smaller than the BMP: use BMP to PNG. If it has to be a JPG and the picture is mostly text or lines, leave the quality at its starting 92% or move it higher, where the smudging is hard to see.

Transparency, colour depth, and DPI#

Most BMP files have no transparency, but a 32-bit BMP can. A JPEG cannot store it, so any transparent pixels are filled white. A BMP with 256 colours or fewer converts to a full colour JPG with the same colours, since JPEG always stores full colour.

A BMP from a scanner often records the resolution it was scanned at, such as 300 DPI. The JPG keeps the scan's full size in pixels but not that number, so a print shop may read it as 72 or 96 DPI. If it asks for 300, set it again with the DPI changer, which changes the label and leaves the pixels alone.