PNG is a versatile lossless format with transparency support. PNG opens in most environments, but another format such as BMP may suit some uses better.
BMP is Windows' basic bitmap that stores pixels as they are, without compression. When you convert PNG to BMP, a solid background replaces transparency and the file grows. See the comparison below for what changes.
This converter reads the file itself to confirm it is PNG, then converts it to BMP right in your browser. Your image is never uploaded.
PNG vs BMP: what's the difference?
| Item | PNG | BMP |
|---|---|---|
| Compression | Lossless | None (uncompressed) |
| Transparent background | Yes | No |
| Animation | No | No |
| Introduced | 1996 | 1990 |
| Support in programs and upload forms | nearly everywhere | broad |
| Shown directly in browsers | Yes | Yes |
| Photo file size (JPG = 1) | about 3× | about 12× |
What is PNG?
PNG (Portable Network Graphics) is a lossless format created in 1996 to avoid the patent problems around GIF. Because not a single pixel changes when you save and reopen it, it suits original artwork that goes through many edits.
What is BMP?
BMP is a bitmap format from Windows that mostly stores pixel values as they are, without compression. Its simple structure makes it easy for programs to read, but the files are so large that it is rarely used on the web.
What changes when you convert PNG to BMP
Transparent areas are filled with the background color you choose
BMP can't represent transparency. Transparent and semi-transparent areas are composited onto the background color in the options (white by default), so pick a matching color first if the image will be used on a dark screen.
Pixel values are preserved exactly
PNG and BMP are both lossless, so there is no change in quality. Only the file structure, compatibility and size differ.
With no compression, the file size grows a lot
BMP stores pixels as they are. A 1920×1080 image becomes about 6MB, so unless equipment or software requires BMP, another format is recommended.
BMP has no quality setting
BMP is none (uncompressed), so the quality slider doesn't apply. Instead, when converting from PNG you can manage file size by resizing (exact width and height, or a percentage).
How the file size changes
For the same photo, BMP is much larger than PNG (roughly 4× or so). This is for photos; for simple images such as logos and screenshots, PNG can actually come out smaller.
BMP has narrower support than PNG
PNG support is nearly everywhere and BMP support is broad. Check that the recipient can open BMP first, and if you're not sure, JPG or PNG is safer.
When to convert
- You need to feed legacy equipment or embedded software that only reads BMP
- You're preparing an image for typical BMP uses (input for legacy equipment and software, simple image-processing exercises)
- You want to tidy a PNG file into a format that's easier to edit or archive
PNG → BMP: practical tips
Use BMP only when legacy equipment or software requires it. The file becomes several times the size of the PNG. Transparent areas are filled with the background color you choose.