BMP to PNG Converter
Convert BMP bitmap images to PNG format with lossless compression. Dramatically reduce file size while keeping perfect quality.
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What is BMP to PNG Conversion?
BMP (Bitmap) is an uncompressed image format that stores raw pixel data, resulting in very large file sizes. PNG uses lossless compression to achieve much smaller files without any loss in quality. A BMP file can easily be 10-50x larger than its PNG equivalent.
When to Convert BMP to PNG
Convert BMP to PNG when you need to reduce file size for sharing, uploading to websites, or saving storage space. PNG preserves every pixel of the original BMP while compressing the data efficiently. It also adds transparency support that BMP lacks.
How to Use
- Drag and drop your BMP files onto the upload area, or click to browse.
- You can add multiple files at once for batch conversion.
- Click "Convert to PNG" to start the conversion.
- Download individual files or use "Download All" to get everything.
BMP background
BMP (Microsoft Windows Bitmap, 1990) stores raw uncompressed pixel data — typically 3-4 bytes per pixel. A 1920×1080 image is ~8 MB as BMP but compresses to under 1 MB as PNG without any quality loss. BMP is rarely used today except for system icons (Windows wallpaper format), legacy software, and occasionally for fast-load embedded systems.
You’d encounter BMP files when: rescuing old Windows screenshots, working with legacy CAD/GIS software, processing default Windows wallpapers, dealing with old digital camera exports, or extracting from .exe resources.
A Format From 1986 That Refuses to Die
BMP was Microsoft’s bitmap format for Windows 1.0, and its defining characteristic is that it barely compresses at all. Every pixel is written out in full, so a 1920×1080 image occupies roughly 6 MB no matter what it contains — a photograph, a screenshot, or a solid white rectangle all cost the same.
That was a deliberate trade in 1986, when CPU time was scarce and reading a file without decoding it was worth the disk space. Today it is simply waste. PNG stores the same pixels exactly, with no quality loss whatsoever, and typically lands somewhere between a tenth and a half of the size depending on the content.
You still meet BMP in specific places: Windows screenshot tools, scientific and medical imaging equipment, older scanners, industrial machine vision cameras, and legacy line-of-business software that has not been touched in twenty years.
Nothing Is Lost in This Conversion
PNG uses lossless compression, which means the decoded image is bit-for-bit identical to the source. This is not a case of quality being “good enough” — the pixels are the same numbers. You can convert BMP to PNG and back again indefinitely without any degradation.
The savings come entirely from how the data is stored. PNG applies a filtering step that turns each row into differences from its neighbours, then compresses the result with DEFLATE. Flat colour, gradients, repeated patterns, and text all compress dramatically. Photographic noise compresses least, which is why a photograph saved as PNG shrinks less than a screenshot does.
FAQ
How much smaller will the PNG be compared to BMP?
Photos: typically 2-10× smaller. Graphics with solid colors / hard edges (logos, screenshots): up to 50× smaller. The biggest gains come from images with limited color palettes that PNG’s DEFLATE compression handles efficiently.
Is there any quality loss?
No. Both BMP and PNG are lossless formats — every pixel is preserved exactly. The conversion only changes the storage encoding.
Why are BMP files so large?
BMP stores raw pixels with no compression. A 1920×1080 image at 24-bit color = 1920 × 1080 × 3 = ~6.2 MB. PNG compresses similar content to ~500 KB-1 MB.
Does PNG preserve transparency?
Yes — PNG supports full alpha. Most BMP files don’t have transparency (BMP supports it via 32-bit BMP variant, but it’s rare). Output PNG will be fully opaque if input BMP was.
Should I use WebP instead of PNG?
For web display: yes — WebP-lossless is 25-35% smaller than PNG. For maximum compatibility / source files: stick with PNG.
Are my files uploaded?
No — all conversion runs in your browser. Files never leave your device.
How much smaller will the PNG be?
Typically 50–90% smaller. Screenshots, diagrams, and images with flat colour shrink the most; photographs shrink the least because their pixel-to-pixel variation is what compression struggles with.
Is any quality lost?
None. PNG is lossless, so the output contains exactly the same pixel values as the BMP. Only the storage method changes.
Does BMP support transparency?
Some BMP variants technically do, via a 32-bit format with an alpha channel, but support is inconsistent and most tools ignore it. PNG has proper, universally supported transparency, which is another reason to convert.
Should I use PNG or JPG for a BMP?
PNG if the image has text, sharp edges, flat colour, or must stay pixel-exact. JPG if it is a photograph and you want a much smaller file and can accept lossy compression.
Will very large bitmaps work?
Large BMPs are common because the format is uncompressed, and browser memory is the practical limit. Files beyond a few hundred megabytes are better handled by a desktop tool.
Does the colour depth change?
Standard 24-bit and 32-bit bitmaps convert directly. Paletted bitmaps are expanded to full colour, which the PNG then compresses efficiently anyway.
⚠️ Reference Only
Output is generated based on your input and is provided for reference. Results may vary depending on your specific use case, edge cases, or environment-specific behavior. We do not guarantee accuracy of conversions, validations, or computed values.
Always verify critical outputs against official documentation or production environments. We are not responsible for any decisions or losses based on these tool results.