BMP vs PNG — Differences, File Size & When to Use Each

BMP vs PNG

A detailed comparison of BMP Image and PNG Image — file size, quality, compatibility, and which format to choose for your workflow.

Convert BMP → PNG Convert PNG → BMP

BMP

BMP Image

Raster & Vector Images

BMP is an uncompressed raster image format native to Windows. Files are large but preserve exact pixel data with no compression artifacts. Rarely used on the web due to file size.

About BMP files

PNG

PNG Image

Raster & Vector Images

PNG is a lossless image format that supports transparency. It is ideal for graphics, logos, screenshots, and any image where preserving exact pixel data is important.

About PNG files

Strengths Comparison

BMP Strengths

Dead-simple format — trivially easy to read and write.
Lossless and uncompressed — perfect bit-exact pixel storage.
Universally supported in Windows applications since 1985.
Supports 1, 4, 8, 16, 24, and 32-bit color depths.

PNG Strengths

Lossless compression — every save preserves the original pixels perfectly.
Full 8-bit alpha channel for smooth transparency.
Excellent for text, UI screenshots, logos, and line art.
Royalty-free and an ISO standard (ISO/IEC 15948).
Supports 16-bit color depth for high-fidelity work.

Limitations

BMP Limitations

Enormous file sizes — no meaningful compression in typical use.
Not a web format — browsers support it but nobody serves BMPs over HTTP.
No metadata support (no EXIF, no ICC profile in practice).
Multiple header versions mean "a BMP" is ambiguous — parsers must handle several variants.

PNG Limitations

Much larger than JPEG for photographs (no perceptual compression).
No native animation in most software (APNG support is inconsistent).
No CMYK support — web and screen only, not print.
Metadata capabilities are less rich than JPEG's EXIF.

Technical Specifications

Specification	BMP	PNG
MIME type	image/bmp	image/png
Extensions	.bmp, .dib	—
Compression	None (typical); RLE 4/8 bit (rare)	Lossless — DEFLATE (zlib)
Color depths	1, 4, 8, 16, 24, 32 bits per pixel	—
Byte order	Little-endian	—
Color depth	—	1, 2, 4, 8 or 16 bits per channel
Max dimensions	—	2^31 − 1 pixels per side (2.1 billion)
Transparency	—	Full 8-bit alpha channel
Standard	—	ISO/IEC 15948:2004

Typical File Sizes

BMP

Small icon (32×32) 4 KB
Screenshot (1920×1080) ~6 MB
4K image (3840×2160) ~25 MB
Scanned A4 at 300 dpi ~25 MB

PNG

Icon or small logo 2–20 KB
UI screenshot (1920×1080) 200–800 KB
High-res photo (12 MP) 10–30 MB
Print-ready illustration 5–50 MB

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Frequently Asked Questions

BMP (Bitmap) is a raster image format developed by Microsoft for Windows. It stores images with no compression by default, resulting in large file sizes but pixel-perfect quality. It has been part of Windows since version 1.0.

PNG (Portable Network Graphics) is a lossless raster image format created in 1996 as a patent-free alternative to GIF. It supports transparency, making it ideal for logos, icons, and web graphics.

BMP files open in Windows Paint, Photos, macOS Preview, GIMP, Photoshop, and virtually any image viewer. All Windows applications support BMP natively.

PNG files open natively in all modern operating systems, web browsers, and image editors including Photoshop, GIMP, Paint.NET, and Canva.

PNG is better than BMP in almost every scenario since it provides lossless compression (smaller files), transparency support, and wider cross-platform use. BMP is mainly relevant for legacy Windows applications.

WebP offers 26% smaller file sizes than PNG with equivalent quality. Use WebP for web delivery when browser support is sufficient. Use PNG when maximum compatibility or professional editing workflows are needed.