Total CSS payload and the Core Web Vitals
26.7% of audited sites (51,394) ship under 40 KB of CSS and pass LCP at 89% (1.3s median), whereas the 23.1% shipping over 160 KB drop to 70% (1.9s median).
26.7% of sites use under 40 KB of CSS total CSS payload, and 89% of those sites have a good LCP, against 82% of all sites.
LCP pass rate
Sites with under 40 KB of CSS total CSS payload have a good LCP most often: 89%, against 82% of all sites. Sites with over 160 KB of CSS CSS payload have it least often, at 70%.
Total CSS payload usage
Under 40 KB of CSS is the most used: 26.7% of sites.
The four LCP phases
Across the four LCP sub-parts in Chrome's field data, the largest gap between under 40 KB of CSS and over 160 KB of CSS sits in time to first byte (TTFB): 510 ms median for under 40 KB of CSS against 911 ms for over 160 KB of CSS. Overall median field LCP is 1.3s for under 40 KB of CSS (TTFB 510 ms, load delay 255 ms, load duration 136 ms, render delay 202 ms) versus 1.9s for over 160 KB of CSS.
Understanding total CSS payload
Why stylesheet weight is a direct render blocker
External stylesheets block first paint until every CSS file in the document head is downloaded and parsed into the CSSOM. Across 51,394 sites (26.7%) under 40 KB of CSS, 89% pass field LCP at a 1.3s median, while the 23.1% (44,341) exceeding 160 KB fall to 70% good LCP (1.9s median).
Keep total stylesheet transfer under 80 KB by purging unused utility classes, splitting template CSS per route, and removing legacy icon-font stylesheets. Across all audited sites, 26.7% stay under 40 KB (89% good LCP, 1.3s median) versus 23.1% above 160 KB (70% good LCP, 1.9s median).
How total CSS payload plays out per platform
What the field data shows when you isolate a single CMS or framework.
WordPress 64,981 sites WordPress sites over 160 KB of CSS pass LCP 27 points less often than sites under 40 KB.
Across WordPress sites, 36% ship over 160 KB of stylesheets (58% LCP pass rate, 2.3s median) and 13% ship under 40 KB (85% pass rate, 1.5s median).
Shopify 8,571 sites 60% of Shopify stores transfer under 80 KB of total CSS.
Across Shopify storefronts, 47% transfer 40 to 80 KB of CSS (97% LCP pass rate) and 14% transfer under 40 KB (98%), compared with 89% on the 8% exceeding 160 KB.
React 6,212 sites React sites under 40 KB of external CSS pass LCP 37 points more often than sites over 160 KB.
Across React sites, 55% ship under 40 KB of external CSS (91% good LCP, 1.3s median) and 22% ship over 160 KB (54% good LCP, 2.4s median).
By Arjen Karel · 210,902 crawled sites (196,263 with all devices Chrome field data, 192,293 sites with total CSS payload, October 2026). How we measured.