BMP vs PNG: File Size, Quality, and When to Use Each
Published on March 10, 2026
PNG is almost always the better choice. Both BMP and PNG are lossless formats that preserve full image quality, but PNG compresses the data so files are 50-80% smaller. BMP stores raw, uncompressed pixel data with zero compression, which makes it simple but bloated. Unless you are working with legacy Windows software that requires BMP, PNG does everything BMP does in a fraction of the file size.
File Size
A 1920x1080 image at 24-bit color depth takes about 5.9 MB as a BMP file. The same image saved as PNG is typically 1-2 MB, sometimes less depending on the content. Images with large areas of flat color (screenshots, diagrams, UI mockups) compress especially well in PNG. Photos compress less aggressively but still save 30-50% compared to BMP.
Transparency
PNG supports full alpha transparency, meaning each pixel can have a variable opacity level from fully transparent to fully opaque. BMP has no transparency support at all. If you need transparent backgrounds for logos, icons, or overlays, BMP is not an option. This alone makes PNG the standard for web graphics, app icons, and UI elements.
Color Depth
BMP supports 1-bit, 4-bit, 8-bit, 16-bit, 24-bit, and 32-bit color. PNG supports 1-bit through 48-bit color plus an 8-bit or 16-bit alpha channel. In practice, both handle 24-bit true color (16.7 million colors) just fine for most images. PNG edges ahead when you need 48-bit deep color for professional photo workflows.
Compatibility
PNG works in every browser, image editor, operating system, and messaging app made in the last 20 years. BMP also has wide support but is rarely used outside of Windows-specific applications, embedded systems, and some legacy software. No modern web platform uses BMP -- the files are too large and offer no advantages over PNG on the web.
When to Use Each
- PNG: Web images, screenshots, logos, icons, anything that needs transparency, general-purpose lossless storage.
- BMP: Legacy Windows applications that require it, embedded systems with simple decoders, raw pixel data for image processing pipelines.
If you have BMP files you need to share or upload, converting to PNG or JPG will save significant space. Our PNG to JPG converter can reduce files even further when transparency is not needed.
Related reading: BMP vs JPG covers the uncompressed vs lossy tradeoff, TIFF vs BMP compares two uncompressed-friendly formats, PNG vs JPG covers lossy vs lossless tradeoffs, TIFF vs PNG compares two lossless formats for different use cases, and PNG vs GIF explains when animation matters.