Convert PNG to BMP
This is the only conversion here that trades a good format for an obsolete one, and there is exactly one reason to do it: something downstream reads nothing else. Embedded displays, laboratory instruments, industrial control panels, software from 2003. For them, BMP's simplicity is the feature.
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What it does
- Uncompressed 24-bit output that decodes with no library
- Identical pixels — nothing is lost, only stored inefficiently
- Transparency is flattened, because BMP has none in practice
- No watermark and no sign-up
How to use PNG to BMP
- 1
Add the PNG
Splash screens for a device, icons for legacy software, test patterns for an instrument, or whatever a piece of hardware documentation is demanding as a .bmp.
- 2
Convert
The image is decoded and written out as an uncompressed bitmap on our server. Conversion is instant; the download is the slow part, because the file is large by design.
- 3
Check the dimensions against the device
Embedded targets are usually strict about size, and often about bit depth too. Resize the PNG to the exact panel resolution before converting — a device expecting 320x240 will not scale for you, it will fail.
How it works
The PNG is decoded, any transparency is composited against white, and the pixels are written as an uncompressed 24-bit BMP.
There is no quality decision to make, because there is no compression to tune. BMP stores what it is given.
Where this is genuinely needed
Embedded displays. Small LCD and e-paper panels driven by microcontrollers. The firmware often has no image library at all — the display routine expects a pixel array and a BMP is one with a header attached.
Laboratory and industrial instruments. Oscilloscopes, spectrometers, machine-vision controllers and CNC panels frequently read and write BMP because the format was settled before the instrument was designed and there has been no reason to change.
Legacy Windows software. Applications with resource files, custom skins or icon sets from the era when BMP was the default.
Bootloaders and firmware splash screens. Anything that draws an image before a real operating system is running, where there is no decompression library because there is barely a system.
In every case the requirement comes from the hardware or the software, not from anyone's preference. Nobody chooses BMP.
What to check before converting
Exact dimensions. Embedded targets rarely scale. If the panel is 320x240, the bitmap must be 320x240.
Bit depth. Some devices want 24-bit, some 16-bit, some 8-bit indexed or 1-bit monochrome. This produces 24-bit, which is the most common requirement and not a universal one — check the documentation.
Row order. BMP stores rows bottom-up by convention, and a handful of naive readers assume top-down and display the image upside down. If that happens, the reader is at fault and flipping the source before converting is the practical workaround.
Color order. BMP stores blue, green, red rather than red, green, blue. Any correct reader handles it; a hand-written one sometimes does not, and the symptom is an image with the reds and blues swapped.
If nothing requires it
Do not convert. PNG is better in every measurable way — same pixels, real transparency, a fraction of the size — and BMP offers nothing in return except compatibility with software that has not been updated in twenty years. The reverse conversion is the one most people actually want.
Examples
A splash screen for an embedded display
Nearly thirty times larger, and correct. The device's firmware reads the pixel array straight into its framebuffer with no decoder at all, which is the only reason this format is still specified in 2026.
A logo with a transparent background
The one thing that actually changes. BMP's alpha support exists on paper and is ignored by most software that reads BMP, so transparent pixels are filled rather than left to chance. If the background needs to be another color, composite it in an editor first.
Frequently asked questions
Why would anyone want BMP?
Because it needs no decoder. A 24-bit BMP is a short header followed by raw pixel values in rows, which means a microcontroller with a few hundred bytes of RAM can display one by copying bytes. PNG requires a Deflate decompressor and a filtering pass, which is a real cost on hardware that small. Simplicity is the entire feature.
Does the image lose quality?
No. Both formats store exact pixel values, so the bitmap contains precisely the image the PNG did. The only change is transparency, which is flattened. Everything else — colors, dimensions, sharpness — is bit-for-bit identical, stored far less efficiently.
What happens to transparency?
It is flattened against white. BMP does have a 32-bit variant with an alpha channel, but support for it is inconsistent enough that writing one is a gamble — much of the software that still reads BMP predates the variant and will show garbage or ignore the channel. Flattening produces a file that works everywhere BMP works.
How large will the file be?
Width times height times three bytes, plus a small header, regardless of what the image contains. A 1920x1080 bitmap is always about 6 MB whether it shows a photograph or a solid color. That predictability is exactly why embedded systems like it — the memory requirement is known before the file is read.
Further reading
- The Same Image Was 10 KB as PNG and 7.6 MB as BMPBMP files are famous for being large, and the scale of it still surprises people when they see it directly. The same image, unchanged, was seven hundred and twenty-two times bigger in BMP than in PNG. The reason is simple and worth understanding, because it explains what every other format is doing for you.
- Interlacing a PNG Made It 27% Bigger and Did Not HelpPNG has an interlacing option that shows a rough version of the image while it loads, in the same spirit as progressive JPEG. Unlike progressive JPEG, it is reliably and substantially more expensive — and the preview it produces is worse. Here is what it cost on two very different images.
- PNG's Maximum Compression Setting Is Free and Nobody Uses ItPNG has a compression level from 0 to 9 that almost nobody changes, partly because the name suggests a quality trade-off that does not exist. Every level produces a bit-identical image; the only thing that varies is how long the encoder spends looking for savings. Here is what the highest setting is worth.