Images

What is a BMP file?

Updated Jul 2026

Definition

BMP (Bitmap image) is an old Windows image format that stores every pixel with little to no compression. That makes it lossless, the picture looks exactly as sharp as the original, but it also makes the files much larger than a JPG or PNG of the same image. Most people run into BMP through old software, scanners, or Windows tools like Paint.

BMPBitmap image

Extension: .bmp
Type: Images
Typically: Legacy Windows images
Transparency: None

Why BMP exists

BMP goes back to the early days of Windows, where it was the native image format built into the operating system itself. Paint still saves to it by default in some versions, and plenty of older scanners, screenshot tools, and legacy business software still default to it too.

The format works by storing the color value of every single pixel in the image, in a simple grid, with no compression squeezing the data down. That's why a BMP of a photo can be five or ten times larger than the same photo saved as a JPG. Nothing is lost, but nothing is saved either.

People usually need to convert a BMP because of its size. A folder of BMP screenshots eats up storage fast, email attachments bounce for being too large, and most websites either reject BMP uploads or handle them poorly. Converting to PNG or JPG shrinks the file while keeping it usable everywhere.

The trade-offs

Strengths

Lossless, no compression artifacts or quality loss
Simple format that's been supported by Windows for decades
Easy for old and simple software to read and write

Watch-outs

Very large files compared to JPG or PNG
Poor support outside Windows and older tools
Rarely accepted by websites, email clients, or modern apps
No practical benefit over PNG, which is also lossless but much smaller

A note on privacy

BMP files are usually stripped down, they don't carry EXIF or GPS metadata the way a phone photo does, since the format predates most of that. The bigger privacy concern is just the file itself: if you upload a BMP to convert it, that image sits on someone else's server while it's processed. Converting on your own Mac or Windows machine means the file never leaves your computer.

Convert a BMP file

Questions

How do I open a BMP file?

Any Windows computer opens BMP natively in Paint, Photos, or most image viewers. On a Mac, Preview and most photo apps open it too, though you'll usually want to convert it before sharing.

Is BMP better than PNG?

Both are lossless, but PNG compresses the data first, so a PNG of the same image is almost always much smaller with no quality difference. There's little reason to keep a file as BMP once you can save it as PNG.

Why does my scanner or screenshot tool save as BMP?

Older or simpler software defaults to BMP because it's easy to write and needs no compression logic. Newer versions of the same tools usually let you switch the default format to PNG or JPG.

Can I convert BMP without uploading it?

Yes. A desktop app like Morphjet converts BMP files on your own computer, so nothing gets sent to a server just to change the format.

Morphjet opens and converts BMP and 1,800+ other formats, all on your own computer. Launching this July.