The State of Web Vitals

Synthetic paint milestones on React sites

45.9% of audited sites (4,385) paint their hero element in under 300ms in the lab and pass field LCP at 95% (1.1s median), while the 26.1% exceeding 1,500ms in the lab pass field LCP at just 70% (1.8s 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 →

45.9% of React sites use under 300ms lab LCP synthetic paint milestones, and 95% 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 · 9,561 sites with synthetic paint milestonesBy Arjen Karel · corewebvitals.io/state-of-cwv
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LCP pass rate

Sites with under 300ms lab LCP synthetic paint milestones have a good LCP most often: 95%, against 85% of all React sites. Sites with over 1,500ms lab LCP lab paint time have it least often, at 70%.

SitesGood, needs improvement, poor LCPMedian
All React sites9,11085%1.4s
Under 300ms lab LCP 45.9%4,14495%1.1s
300 to 600ms lab LCP 14.7%1,35486%1.5s
600 to 1,500ms lab LCP 13.3%1,21976%1.9s
Over 1,500ms lab LCP 26.1%2,38470%1.8s
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 · 9,561 sites with synthetic paint milestonesBy Arjen Karel · corewebvitals.io/state-of-cwv
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Synthetic paint milestones usage

Under 300ms lab LCP is the most used: 45.9% of React sites.

Under 300ms lab LCP 45.9% Over 1,500ms lab LCP 26.1% 300 to 600ms lab LCP 14.7% 600 to 1,500ms lab LCP 13.3%
Under 300ms lab LCP 45.9% Over 1,500ms lab LCP 26.1% 300 to 600ms lab LCP 14.7% 600 to 1,500ms lab LCP 13.3%
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field data · 9,561 sites with synthetic paint milestonesBy 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 300ms lab LCP and over 1,500ms lab LCP sits in time to first byte (TTFB): 418 ms median for under 300ms lab LCP against 686 ms for over 1,500ms lab LCP. Overall median field LCP is 1.2s for under 300ms lab LCP (TTFB 418 ms, load delay 417 ms, load duration 138 ms, render delay 157 ms) versus 1.8s for over 1,500ms lab LCP.

Median LCP phase breakdown (Chrome field p75) Load delay Median LCP
React sites with synthetic paint milestones 6,733516 ms440 ms440 mslab 440 ms1.4s
Under 300ms lab LCP 3,059418 ms417 ms417 mslab 417 ms1.2s
600 to 1,500ms lab LCP 917950 ms445 ms227 ms445 mslab 445 ms1.9s
300 to 600ms lab LCP 1,011582 ms462 ms462 mslab 462 ms1.5s
Over 1,500ms lab LCP 1,746686 ms480 ms480 mslab 480 ms1.8s
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 · 9,561 sites with synthetic paint milestonesBy Arjen Karel · corewebvitals.io/state-of-cwv
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Synthetic paint milestones per platform

Wix sets the synthetic paint milestones to under 300ms lab LCP on 63% of its sites, and 94% of Wix sites have a good LCP, against 85% of all sites.

PlatformSynthetic paint milestones on its sitesGood LCP
React sites with synthetic paint milestones 9,561 sitesUnder 300ms lab LCP 46%Over 1,500ms lab LCP 26%300 to 600ms lab LCP 15%600 to 1,500ms lab LCP 13%85%
Wix 5,823 sitesUnder 300ms lab LCP 63%Over 1,500ms lab LCP 21%300 to 600ms lab LCP 11%94%
WordPress 2,336 sitesOver 1,500ms lab LCP 39%600 to 1,500ms lab LCP 29%300 to 600ms lab LCP 19%Under 300ms lab LCP 13%61%
Under 300ms lab LCP Over 1,500ms lab LCP 300 to 600ms lab LCP 600 to 1,500ms lab LCP
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field data · 9,561 sites with synthetic paint milestonesBy Arjen Karel · corewebvitals.io/state-of-cwv
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Synthetic paint milestones or the platform

Does the platform explain the synthetic paint milestones difference?

On Wix, 96% of sites with under 300ms lab LCP synthetic paint milestones have a good LCP, against 91% of Wix sites with over 1,500ms lab LCP. Within Wix, sites with under 300ms lab LCP have a good LCP more often. On WordPress, 86% of sites with under 300ms lab LCP synthetic paint milestones have a good LCP, against 40% of WordPress sites with over 1,500ms lab LCP. Within WordPress, sites with under 300ms lab LCP have a good LCP more often.

How clean lab paint timings translate to real-user field LCP

Synthetic paint milestones measure your page without real-user cellular latency or cold device caches. A page that already takes over 1.5 seconds in a fast lab environment rarely survives real-world mobile networks. Across 4,385 sites (45.9%) painting under 300ms in the lab, 95% pass field LCP (1.1s median), dropping to 70% (1.8s median) on the 26.1% (2,495) over 1,500ms.

The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field data · 9,561 sites with synthetic paint milestonesBy Arjen Karel · corewebvitals.io/state-of-cwv
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Understanding synthetic paint milestones

Optimize unthrottled server TTFB and eliminate render-blocking head resources so the baseline paint path finishes in under 600ms in clean lab conditions. Across all audited sites, 45.9% finish lab LCP under 300ms (95% good LCP, 1.1s median) versus 26.1% above 1,500ms (70% good LCP, 1.8s median).

Go fix it How we measured → Chrome DevTools network settings for CWV testing →
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field data · 9,561 sites with synthetic paint milestonesBy Arjen Karel · corewebvitals.io/state-of-cwv
Related signals Total Blocking Time (lab) → Main-thread CPU (lab) → Document lifecycle (lab) → By Arjen Karel · 9,570 crawled React sites (9,110 with all devices Chrome field data, 9,561 sites with synthetic paint milestones, October 2026) · How we measured