Why WebP Beats JPG and PNG
WebP produces files 25–35% smaller than JPG at equivalent visual quality, and 60–80% smaller than PNG for photographs. For web use it's the single highest-impact image optimization available in modern browsers.
What This Tool Does
- Reads the selected image via
FileReader - Loads it into an off-screen
<img>element - Draws it onto a
<canvas>, optionally resizing - Calls
canvas.toBlob(cb, 'image/webp', quality) - Displays the resulting size and preview
All steps execute in your browser's memory. Nothing is uploaded anywhere.
Quality Guidelines
| Content | Quality |
|---|---|
| Photography (hero images) | 0.80–0.85 |
| Product photos | 0.85–0.92 |
| Thumbnails / previews | 0.60–0.70 |
| Screenshots / UI | 0.90–0.95 |
| Logos / flat graphics | PNG may still be smaller — compare |
Responsive Images
Don't ship the same huge image to every device. Generate 2–3 sizes (e.g., 640, 1280, 1920 widths), save each as WebP, and use <picture> or srcset to serve the right one:
<picture>
<source srcset="hero-640.webp 640w, hero-1280.webp 1280w, hero-1920.webp 1920w"
sizes="(max-width: 600px) 640px, (max-width: 1200px) 1280px, 1920px"
type="image/webp">
<img src="hero-1280.jpg" alt="Hero" />
</picture>
Browser Support
WebP is supported by Chrome 32+, Firefox 65+, Safari 14+, Edge 18+. That's ~97% of users in 2026. Use <picture> with a JPG fallback for the remaining 3%.
What to Watch For
- WebP can look worse than JPG at low quality settings on photos — start at 0.82.
- Images with transparency (PNG) preserve alpha in WebP lossless mode, but quality applies differently.
- Very large images (4K+) can take 1–3 seconds to convert — this tool processes 10–15 MP in under a second on modern hardware.
- Always visually compare the preview — file size is only useful if quality is acceptable.