LCP image byte weight on Wix sites

Sites with an LCP image under 40 KB LCP image byte weight have a good LCP most often: 93%, against 92% of all Wix sites. Sites with an LCP image between 40 and 100 KB hero image size have it least often, at 91%.

An LCP image under 40 KB is the most used: 60.9% of Wix sites.

Across the four LCP sub-parts in Chrome's field data, the largest gap between an LCP image under 40 KB and an LCP image between 40 and 100 KB sits in time to first byte (TTFB): 375 ms median for an LCP image under 40 KB against 298 ms for an LCP image between 40 and 100 KB. Overall median field LCP is 1.2s for an LCP image under 40 KB (TTFB 375 ms, load delay 477 ms, load duration 249 ms, render delay 141 ms) versus 1.2s for an LCP image between 40 and 100 KB.

React sets the LCP image byte weight to an LCP image under 40 KB on 61% of its sites, and 92% of React sites have a good LCP, against 92% of all sites.

FrameworkLCP image byte weight on its sitesGood LCP

Wix sites with LCP image byte weight 3,960 sitesUnder 40 KB hero image 61%40 to 100 KB hero image 32%92%

React 3,959 sitesUnder 40 KB hero image 61%40 to 100 KB hero image 32%92%

Under 40 KB hero image 40 to 100 KB hero image 100 to 300 KB hero image Over 300 KB hero image

Does the framework explain the LCP image byte weight difference?

On React, 93% of sites with an LCP image under 40 KB LCP image byte weight have a good LCP, against 91% of React sites with an LCP image between 40 and 100 KB. Within React, sites with an LCP image under 40 KB and an LCP image between 40 and 100 KB have a good LCP about equally often.

How intrinsic versus rendered megapixels waste hero bandwidth

The median LCP image is 0.23 intrinsic megapixels rendered into a 0.12 megapixel slot. Serving unresized desktop banners to mobile viewports inflates hero transfer bytes and extends LCP load duration. Across 2,411 sites (60.9%) with a hero image under 40 KB, 93% pass field LCP (1.2s median), dropping to 100% (1.0s median) on the 0.5% (18) exceeding 300 KB.