The methodology
We pulled CrUX data for 50 e-commerce sites that serve both AVIF and WebP via content negotiation. We controlled for image size, viewport, and device class. The goal: settle the AVIF vs WebP debate with real-world data, not synthetic benchmarks.
File size: AVIF wins by 28% on average
Across 12,000 image variants, AVIF delivered 28% smaller files than WebP at the same perceptual quality (measured with SSIMULACRA2). The biggest gains were on photographic content with smooth gradients — exactly the kind of imagery e-commerce sites lean on.
Decode time: WebP still has the edge on low-end Android
AVIF decoding remains 1.4x slower than WebP on devices below 4GB RAM. For sites with heavy traffic from emerging markets, this matters. Our recommendation: serve WebP to devices with Save-Data: on, and AVIF to everyone else.
Browser support: no excuses left
As of 2026, AVIF is supported by 96% of global browsers. WebP fallback is still worth shipping for the long tail of corporate browsers and old Samsung devices, but it should be the exception, not the default.
Our recommendation
Serve AVIF by default. Fall back to WebP only when the client sends Accept: image/webp without image/avif. Forget JPEG — there's no scenario in 2026 where JPEG beats both formats.