The State of Web Vitals

Total CSS payload on React sites

54.8% of audited sites (3,404) ship under 40 KB of CSS and pass LCP at 91% (1.3s median), whereas the 22.5% shipping over 160 KB drop to 54% (2.4s median).

Field data PhoneDesktopAll Scope All sites October 2026 edition · All devices field outcomes · React sites only
React Scoped to 9,570 sites out of 210,902 analyzed (frameworks) Compare with all sites →

54.8% of React sites use under 40 KB of CSS total CSS payload, and 91% of those sites have a good LCP, against 85% of all React sites.

The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field data · 6,212 sites with total CSS payloadBy Arjen Karel · corewebvitals.io/state-of-cwv
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LCP pass rate

Sites with under 40 KB of CSS total CSS payload have a good LCP most often: 91%, against 85% of all React sites. Sites with over 160 KB of CSS CSS payload have it least often, at 54%.

SitesGood, needs improvement, poor LCPMedian
All React sites9,11085%1.4s
Under 40 KB 54.8%3,23791%1.3s
40 to 80 KB 8.4%50385%1.6s
80 to 160 KB 14.3%86268%2.0s
Over 160 KB 22.5%1,34354%2.4s
GoodNeeds improvementPoorSites: with Chrome field data
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field data · 6,212 sites with total CSS payloadBy Arjen Karel · corewebvitals.io/state-of-cwv
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Total CSS payload usage

Under 40 KB of CSS is the most used: 54.8% of React sites.

Under 40 KB 54.8% Over 160 KB 22.5% 80 to 160 KB 14.3%
Under 40 KB 54.8% Over 160 KB 22.5% 80 to 160 KB 14.3% 40 to 80 KB 8.4%
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field data · 6,212 sites with total CSS payloadBy Arjen Karel · corewebvitals.io/state-of-cwv
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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): 439 ms median for under 40 KB of CSS against 1263 ms for over 160 KB of CSS. Overall median field LCP is 1.3s for under 40 KB of CSS (TTFB 439 ms, load delay 456 ms, load duration 146 ms, render delay 158 ms) versus 2.4s for over 160 KB of CSS.

Median LCP phase breakdown (Chrome field p75) Load delay Median LCP
React sites with total CSS payload 4,448617 ms444 ms444 mslab 444 ms1.6s
80 to 160 KB 6551110 ms369 ms268 ms369 mslab 369 ms2.0s
40 to 80 KB 375660 ms373 ms373 mslab 373 ms1.6s
Under 40 KB 2,389439 ms456 ms456 mslab 456 ms1.3s
Over 160 KB 1,0291263 ms490 ms273 ms490 mslab 490 ms2.4s
TTFB Resource load delay Resource load time Element render delay
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field data · 6,212 sites with total CSS payloadBy Arjen Karel · corewebvitals.io/state-of-cwv
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Total CSS payload per platform

Wix sets the total CSS payload to under 40 KB of CSS on 95% of its sites, and 94% of Wix sites have a good LCP, against 85% of all sites.

PlatformTotal CSS payload on its sitesGood LCP
React sites with total CSS payload 6,212 sitesUnder 40 KB 55%Over 160 KB 22%80 to 160 KB 14%85%
Wix 2,727 sitesUnder 40 KB 95%94%
WordPress 2,319 sitesOver 160 KB 50%80 to 160 KB 31%40 to 80 KB 12%61%
Under 40 KB Over 160 KB 80 to 160 KB 40 to 80 KB
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field data · 6,212 sites with total CSS payloadBy Arjen Karel · corewebvitals.io/state-of-cwv
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Total CSS payload or the platform

Does the platform explain the total CSS payload difference?

On Wix, 93% of sites with under 40 KB of CSS total CSS payload have a good LCP, against 95% of Wix sites with 40 to 80 KB of CSS. Within Wix, sites with under 40 KB of CSS and 40 to 80 KB of CSS have a good LCP about equally often. On WordPress, 75% of sites with under 40 KB of CSS total CSS payload have a good LCP, against 52% of WordPress sites with over 160 KB of CSS. Within WordPress, sites with under 40 KB of CSS have a good LCP more often.

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 3,404 sites (54.8%) under 40 KB of CSS, 91% pass field LCP at a 1.3s median, while the 22.5% (1,397) exceeding 160 KB fall to 54% good LCP (2.4s median).

The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field data · 6,212 sites with total CSS payloadBy Arjen Karel · corewebvitals.io/state-of-cwv
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Understanding total CSS payload

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, 54.8% stay under 40 KB (91% good LCP, 1.3s median) versus 22.5% above 160 KB (54% good LCP, 2.4s median).

Go fix it Eliminate render-blocking resources → Remove unused CSS →
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field data · 6,212 sites with total CSS payloadBy Arjen Karel · corewebvitals.io/state-of-cwv
Related signals Script loading mix → Font source → Image format mix → Iframe loading → By Arjen Karel · 9,570 crawled React sites (9,110 with all devices Chrome field data, 6,212 sites with total CSS payload, October 2026) · How we measured