Why can’t a PNG portrait be compressed to 20KB without shrinking its resolution?

PNG is a lossless format without a quality quantization table. Converting that PNG to JPEG or WebP lets our 7-pass engine lock it under 20KB at full resolution.

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Compress JPEG vs. WebP vs. PNG: Which Format Is Best for Exact KB Limits?

Reviewed by CompressPhoto Biometric & Imaging Lab • Updated & Verified: November 2026 • Standard Format: Custom Width × Height (JPG · WebP · PNG) — Target: 10 KB – 500 KB Custom

Choosing the wrong image format is the #1 reason people struggle to get a photo under 15 KB, 20 KB, or 30 KB. Understanding how JPEG, WebP, and PNG store pixels lets you pick the best format for any upload portal or website.

Format Comparison: JPG vs. WebP vs. PNG

Each format uses a completely different compression math inside the browser:

JPEG (.jpg): Universal compatibility. Required by 99% of government passport, visa, and exam portals. Supports precise 7-pass quantization to hit 10 KB–500 KB.
WebP (.webp): Modern web format that delivers 25–35% sharper details than JPEG at the exact same KB size. Best for websites, blogs, and modern portals.
PNG (.png): Lossless compression. Great for logos, but a 600×600 portrait in PNG weighs 350 KB+. Always convert PNG portraits to JPG or WebP when you need < 50 KB!

Frequently Asked Questions

Why can’t a PNG portrait be compressed to 20KB without shrinking its resolution?: PNG is a lossless format without a quality quantization table. Converting that PNG to JPEG or WebP lets our 7-pass engine lock it under 20KB at full resolution.