Definition
WebP (developed by Google) and AVIF (based on the AV1 codec) are image formats offering significantly better compression than JPEG and PNG. WebP reduces image size by 25-35% compared to JPEG at equivalent quality. AVIF goes further with 50%+ reduction. For SEO, these formats reduce page weight, improve load time, and Core Web Vitals (LCP in particular). Google PageSpeed Insights explicitly recommends next-gen formats. Implementation uses the <picture> tag with fallbacks (AVIF > WebP > JPEG) or server-side content negotiation (Accept header). Modern CDNs can also convert images automatically.
Key Points
- WebP reduces size 25-35% vs JPEG, AVIF by 50%+
- Use the picture tag with multiple sources and JPEG fallback
- CDNs like Cloudflare can convert images automatically
Practical Examples
Automatic CDN conversion
A site enables automatic WebP/AVIF conversion on Cloudflare Polish. Without modifying a single image, total image weight is reduced by 40%, improving LCP by 800ms.
Picture tag with fallbacks
A site implements <picture><source type='image/avif'><source type='image/webp'><img src='fallback.jpg'></picture> for hero images. Modern browsers load AVIF (60% lighter) while older ones receive JPEG.
Frequently Asked Questions
WebP is supported by all modern browsers (Chrome, Firefox, Safari 14+, Edge). AVIF is supported by Chrome, Firefox, and Safari 16.4+. Use the <picture> tag with fallbacks for compatibility.
Ideally both, with AVIF priority and WebP fallback. AVIF offers better compression but slower encoding. If choosing only one, WebP is the most universally supported.
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Last updated: 2026-02-07