Total image payload and the Core Web Vitals
28.7% of audited sites (59,126) transfer 1 to 3 MB of images and 23.7% exceed 3 MB. Sites staying under 350 KB pass LCP at 86% (1.2s median), compared with 83% (1.5s median) above 3 MB.
22.8% of sites use 350 KB to 1 MB of images total image payload, and 89% of those sites have a good LCP, against 86% of all sites.
LCP pass rate
Sites with 350 KB to 1 MB of images total image payload have a good LCP most often: 89%, against 86% of all sites. Sites with over 3 MB of images image payload have it least often, at 83%.
Total image payload usage
1 MB to 3 MB of images is the most used: 28.7% of sites. 350 KB to 1 MB of images is 22.8% of sites.
The four LCP phases
Across the four LCP sub-parts in Chrome's field data, the largest gap between 350 KB to 1 MB of images and over 3 MB of images sits in time to first byte (TTFB): 532 ms median for 350 KB to 1 MB of images against 670 ms for over 3 MB of images. Overall median field LCP is 1.3s for 350 KB to 1 MB of images (TTFB 532 ms, load delay 279 ms, load duration 105 ms, render delay 190 ms) versus 1.5s for over 3 MB of images.
Understanding total image payload
How total image weight competes with the hero paint
Even when off-screen images are lazy-loaded, oversized carousels, unresized product grids, and CSS background images compete for cellular bandwidth during initial viewport load. Across 51,103 sites (24.8%) under 350 KB of images, 86% pass field LCP at a 1.2s median, whereas the 23.7% (48,926) exceeding 3 MB drop to 83% good LCP (1.5s median).
Keep total image transfer under 1 MB on initial load by serving AVIF or WebP, matching srcset widths to rendered layout slots, and lazy-loading off-screen media. Across all audited sites, 24.8% stay under 350 KB (86% good LCP, 1.2s median) versus 23.7% above 3 MB (83% good LCP, 1.5s median).
How total image payload plays out per platform
What the field data shows when you isolate a single CMS or framework.
WordPress 65,509 sites WordPress sites shipping over 3 MB of images pass LCP 12 points less often than sites under 350 KB.
Across WordPress sites, 35% transfer 1 to 3 MB of images and 31% exceed 3 MB. Sites under 350 KB pass LCP at 83% (1.5s median) compared with 71% (1.9s median) above 3 MB.
Shopify 8,573 sites 50% of Shopify storefronts transfer over 1 MB of images.
Across Shopify storefronts, 36% transfer 350 KB to 1 MB of images and 35% transfer 1 to 3 MB. Stores under 350 KB pass LCP at 98% (1.1s median) compared with 94% on stores over 3 MB.
React 9,570 sites React apps exceeding 3 MB of images pass LCP 19 points less often than apps under 350 KB.
Across React sites, 38% transfer under 350 KB of images (86% good LCP, 1.3s median) compared with 14% transferring over 3 MB (67% good LCP, 1.9s median).
By Arjen Karel · 210,902 crawled sites (69,745 with desktop Chrome field data, 206,206 sites with total image payload, October 2026). How we measured.