Choosing the right image format isn't about aesthetics — it's about bytes. The wrong choice costs your users real bandwidth.
Here's a practical decision framework:
SVG
Best for: logos, icons, illustrations, charts
File size: tiny (text-based)
Scaling: infinite (it's math, not pixels)
Don't use for: photos (file size explodes — a single photo as SVG = megabytes)
PNG
Best for: screenshots, UI mockups, images needing transparency
Compression: lossless (every pixel preserved)
Trade-off: larger than lossy formats. A PNG screenshot at 2400px wide is often 500KB+ while the JPG equivalent is 80KB.
WebP
Best for: photos on the web, hero images, anything currently JPG or PNG
Compression: lossy (like JPG) or lossless (like PNG) — your choice
Real-world: 25-35% smaller than equivalent JPG at same quality. Google's format, supported everywhere now (97% browser coverage).
JPEG
Still the universal fallback. Use when you need guaranteed compatibility (email attachments, legacy CMS).
My personal defaults:
- Screenshots for docs → PNG (need pixel-perfect)
- Hero images, blog photos → WebP at quality 80
- User uploads, email → JPEG at quality 85
A quick benchmark from my own site: switching hero images from PNG to WebP saved 1.2MB on first load. That's 0.3s on 3G.
If you need to batch-convert existing images, U-Ultra/Unity's format converter handles SVG↔PNG, HEIC→WebP, and RAW→JPG without installing anything. For local CLI work, I use imgbatch convert *.png --to webp.
What's your go-to format stack?
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