AVIF vs WebP: choosing your image format for LCP

AVIF vs WebP: choosing your image format for LCP

Modern image formats shrink files dramatically, and smaller files mean faster LCP — Largest Contentful Paint. Two names matter: WebP and AVIF.

Think of them like vacuum-packing: same photo, far less space. WebP typically saves around 25-35% versus JPEG. AVIF goes further, often 50% smaller, though it encodes more slowly.

The smart move is offering both with a fallback, so each browser takes what it supports.

1. Use the <picture> tag with AVIF first, WebP next, JPEG last.
2. The browser picks the first format it understands.
3. Old browsers quietly fall back to the JPEG — nobody breaks.

That fallback chain is the trick that makes it safe to adopt today.

Try this: convert your single heaviest image to AVIF, drop it in a <picture> tag, and compare the new file size. The shrink is often jaw-dropping.