BMP files are big because they are not compressed at all. Shrink them as lossless PNG, as a compressed RLE bitmap or as an 8-bit BMP - and see the real size before you download. Want a JPG instead? Use BMP to JPG.
Click a file to preview it. Sizes are measured on the real output.
Changes apply to every file and are measured again.
Each option is measured on your file, but this is what to expect.
| Output | Lossless? | Typical saving | Opens in |
|---|---|---|---|
| PNG | Always | 60-95% | Everything |
| BMP RLE8 / RLE4 | Up to 256 / 16 colours | 70-98% on flat graphics | Windows, Paint, Photoshop, browsers |
| 8-bit BMP | Up to 256 colours | About 66% | Every program that reads BMP |
| 24-bit BMP | Yes | Only by resizing | Every program that reads BMP |
Need the bitmap in another format? BMP to PNG gives you more PNG options, and BMP to WebP makes the smallest web image.
Most of the time a BMP should simply become a PNG.
Legacy software, games and some industrial machines read only BMP.
Use 8-bit BMP - every BMP reader supports it.
Installers, boot screens and resource files often expect a .bmp.
RLE keeps them small and Windows reads it.
Microcontroller displays need a fixed colour depth.
Pick 16 or 2 colours to match the screen.
A standard BMP stores every pixel as three bytes with no compression at all. A 1920 x 1080 picture is always about 6 MB, whether it shows a photo or a plain white page.
That is why converting or compressing a BMP usually saves 50-95%.
PNG is the best choice for almost everyone: it keeps every pixel exactly and is usually 3-10 times smaller. Every app, browser and phone opens it.
If you must keep the .bmp extension, use BMP RLE (compressed bitmap) or 8-bit BMP. Press Compare all to see the measured size of each option for your own file.
PNG output is always lossless. RLE and 8-bit BMP are lossless when the image has 256 colours or fewer - screenshots, icons, diagrams and pixel art often do. The tool counts the colours and tells you.
Photos have thousands of colours, so 8-bit and RLE reduce them to a 256-colour palette. Dithering keeps gradients smooth.
RLE (run-length encoding) stores "200 white pixels" instead of 200 separate white pixels. It is built into the BMP format for 256-colour (RLE8) and 16-colour (RLE4) images.
It works great for flat graphics and poorly for photos. Windows, Paint, Photoshop and browsers open RLE bitmaps, but a few old or embedded programs only read uncompressed BMP - then use 8-bit BMP.
Not with PNG, and not with RLE or 8-bit when your image has 256 colours or fewer. Look at the before and after preview - the row also says Lossless or Colours reduced.
Need to shrink a photo much further? Save it as JPG with BMP to JPG or as WebP with BMP to WebP.
Yes. Drop up to 50 BMP files. They all use the same settings, and three or more download as one ZIP with a short README. If a file cannot get any smaller, the original is kept.
Each file can be up to 200 MB or 50 megapixels. Very big bitmaps take a few seconds because everything runs on your own computer.
Fewer pixels always means a smaller file, so the Resize option helps a lot - or use the Image Resizer for exact sizes.
No. The bitmap is decoded, compressed and measured inside your browser, so your files never leave your device.
