How to use it
- Pick the colour for transparent areas. Many devices expect white or black.
- Drop in your PNGs.
- Download the BMP files.
Choosing the fill colour
PNGs often have transparent backgrounds, and a 24-bit BMP has nowhere to store transparency. The background colour you choose fills those areas. For e-paper and OLED displays, black or white is usually what the display library expects; for embroidery and engraving software, white typically means “nothing here”.
Sizing for a device
Small screens want exact dimensions: 128 × 64, 240 × 240, 296 × 128 and so on. Resize the PNG to the display's resolution with the resizer (untick “Keep proportions” only if you do not mind distortion, or crop to the right shape first), then convert. For one-colour displays, making the image pure black and white first gives cleaner results than letting the device threshold it.
File size
BMP files are uncompressed, three bytes per pixel. A 240 × 240 display image is about 170 KB as BMP whatever it shows, and a full HD image about 6 MB.
PNG and BMP compared
| PNG | BMP | |
|---|---|---|
| First released | 1996 | 1985 |
| Compression | Lossless | Usually none |
| Transparency | Yes, including soft edges | Rarely |
| Animation or pages | Only as APNG, rarely used | No |
| Best for | Screenshots, graphics, text and transparency | Older Windows software and devices |
| Support | Universal | Most desktop software |
Questions people ask
What happens to transparency?
It is filled with the background colour you choose.
Can I make a 1-bit or 16-bit BMP?
This tool writes 24-bit BMP, the most widely readable kind.
Is PNG to BMP lossless?
Yes for colour. Only transparency is flattened.