Why BMP files are so large
BMP is the classic Windows bitmap format. In the 24-bit form that most programs write, it is uncompressed: every pixel is stored as three bytes, one each for red, green and blue. That makes the size easy to predict. A 1920 × 1080 image takes 1920 × 1080 × 3 = 6,220,800 bytes, about 5.9 MB, no matter what the picture shows. The same image as a JPG is often only a few hundred KB.
That is why BMP files from older scanning software, Paint or legacy programs are worth converting before you email, upload or archive them.
How to use it
- Drag your files onto the page or click to choose them. BMP files are accepted, and so is any other image your browser can read.
- Choose the output with the chips: JPG (default), PNG, WebP or BMP.
- For JPG or BMP output, pick a background color. It fills any transparent areas, since neither format keeps transparency here.
- Download the converted files one by one or as a single ZIP.
Everything runs in your browser on your own device, so the files are never uploaded.
Which format to pick
| Output | Choose it when |
|---|---|
| JPG | The BMP is a photo or a scan and you want the smallest file |
| PNG | It is a screenshot, diagram or graphic with text and sharp edges |
| WebP | The image is going on a website |
| BMP | A program or device specifically requires BMP |
PNG is the safest replacement when you are not sure. It is lossless like BMP, so nothing in the image changes, yet it is usually much smaller because it is compressed. JPG gives the smallest files for photos but discards a little detail.
When you still need BMP
Some older Windows programs, industrial and lab software, embedded displays and small hobby electronics projects can only read BMP. For those, convert your image to BMP here. The tool writes a 24-bit uncompressed BMP, the most widely readable variant.
Keep two things in mind. First, the BMP has no transparency, so transparent areas are filled with the background color you choose. Second, the file will be large by design; that is the price of being uncompressed. If the device needs a specific pixel size, resize the image before converting. For program and shortcut icons, the ICO format is usually the better fit; see PNG to ICO.
Frequently asked questions
Does converting BMP to PNG lose quality?
No. PNG is lossless, so every pixel is kept exactly. Only the file size changes.
Why is my new BMP bigger than the original JPG?
BMP output is uncompressed, so its size depends only on the pixel dimensions. That is normal for the format.
Can the BMP keep transparency?
No. The tool writes 24-bit BMP files, which have no transparency channel. Transparent areas are filled with the background color.
How do I make the converted JPG even smaller?
Run it through Compress image, which lets you lower the quality and limit the width. You can read more about the format on the BMP format page.