Image format mix
The image mix by format (JPEG, PNG, WebP, AVIF, SVG, GIF) - counts and bytes per format.
At a glance the headline numbers for Image format mix
The image mix by format (JPEG, PNG, WebP, AVIF, SVG, GIF) - counts and bytes per format.
5.5% of images are AVIF. 29.1% are still JPEG.
The image format mix mix who uses what, and how fast each group loads
Image format mix. On the fleet: 29.1% jpg, 22.1% png, 19.1% webp. 72.4% of sites use at least one jpg.
Jpg leads by count (29.1%) and by bytes (53.8%). computed
Passing INP per bucket every category and count level at once - color is the pass rate
Each row is a category, each column its own count bucket (few on the left, many on the right); the cell is the share of those sites passing INP.
No category moves the INP pass rate much, however many a site ships. computed
Few vs many - does quantity cost INP? the pass rate with few vs many of each category
Per category: the pass rate among pages with FEW of it (hollow ring) against pages with MANY (solid dot), worst trend first. Thin buckets are excluded from the endpoints.
More Other costs the most: the INP pass rate falls from 99% with few to 96% with many. computed
Why this matters for the Core Web Vitals, and where to start fixing it
Image bytes are usually the biggest slice of page weight, and the format multiplies all of them. AVIF and WebP deliver the same picture in far fewer bytes than JPEG. PNG belongs to screenshots and graphics, not photos. GIF is the most expensive way ever invented to ship a short video.
Nobody converts by hand at scale. An image CDN or build step negotiates the best format per browser from one source file. This mix mostly measures how many sites have that step in place.
How does this affect the Core Web Vitals?
Image format mix correlates with the LCP. With AVIF, 90% of sites pass the LCP. With Other, 84% do.
Chrome field data from 94,910 sites, representing millions of real page loads. How we measured.