Total image payload and the Core Web Vitals
28.7% of audited sites (59,575) transfer 1 to 3 MB of images and 23.7% exceed 3 MB. Sites staying under 350 KB pass LCP at 86% (1.3s median), compared with 77% (1.7s median) above 3 MB.
24.8% of sites use under 350 KB of images total image payload, and 86% of those sites have a good LCP, against 82% of all sites.
LCP pass rate
Sites with under 350 KB of images total image payload have a good LCP most often: 86%, against 82% of all sites. Sites with over 3 MB of images image payload have it least often, at 77%.
Total image payload usage
1 MB to 3 MB of images is the most used: 28.7% of sites. Under 350 KB of images is 24.8% of sites.
The four LCP phases
Across the four LCP sub-parts in Chrome's field data, the largest gap between under 350 KB of images and over 3 MB of images sits in time to first byte (TTFB): 533 ms median for under 350 KB of images against 763 ms for over 3 MB of images. Overall median field LCP is 1.3s for under 350 KB of images (TTFB 533 ms, load delay 277 ms, load duration 100 ms, render delay 195 ms) versus 1.7s 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 51,421 sites (24.8%) under 350 KB of images, 86% pass field LCP at a 1.3s median, whereas the 23.7% (49,233) exceeding 3 MB drop to 77% good LCP (1.7s 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, 1.3s median) versus 23.7% above 3 MB (77% good LCP, 1.7s median).
How total image payload plays out per platform
What the field data shows when you isolate a single CMS or framework.
WordPress 65,939 sites WordPress sites shipping over 3 MB of images pass LCP 15 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 79% (1.6s median) compared with 64% (2.1s median) above 3 MB.
Shopify 8,634 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% (1.2s median) compared with 92% on stores over 3 MB.
React 9,658 sites React apps exceeding 3 MB of images pass LCP 26 points less often than apps under 350 KB.
Across React sites, 38% transfer under 350 KB of images (92% good LCP, 1.2s median) compared with 14% transferring over 3 MB (66% good LCP, 2.0s median).
By Arjen Karel · 212,308 crawled sites (197,524 with all devices Chrome field data, 207,612 sites with total image payload, October 2026). How we measured.