The State of Web Vitals

CLS shift concentration on React sites

Among sites recording lab layout shifts, 59.3% (2,367) concentrate 95% or more of their CLS into a single shift (90% good field CLS), while 18.3% suffer multiple compounding shifts (81% good field CLS).

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

59.3% of React sites use a single dominant shift CLS shift concentration, and 90% of those sites have a good CLS, against 92% of all React sites.

The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 5,488 with phone field data · 3,993 sites with CLS shift concentrationBy Arjen Karel · corewebvitals.io/state-of-cwv
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CLS pass rate

Sites with a single dominant shift CLS shift concentration have a good CLS most often: 90%, against 92% of all React sites. Sites with mostly one shift shift concentration have it least often, at 75%.

SitesGood, needs improvement, poor CLSMedian
All React sites5,48892%0.00
Single dominant shift (95%+) 59.3%1,36790%0.00
Multiple compounding shifts (<65%) 18.3%45781%0.01
Mostly one shift (65-94%) 22.4%56775%0.01
GoodNeeds improvementPoorSites: with Chrome field data
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 5,488 with phone field data · 3,993 sites with CLS shift concentrationBy Arjen Karel · corewebvitals.io/state-of-cwv
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CLS shift concentration usage

A single dominant shift is the most used: 59.3% of React sites.

Single dominant shift (95%+) 59.3% Mostly one shift (65-94%) 22.4% Multiple compounding shifts (<65%) 18.3%
Single dominant shift (95%+) 59.3% Mostly one shift (65-94%) 22.4% Multiple compounding shifts (<65%) 18.3%
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 5,488 with phone field data · 3,993 sites with CLS shift concentrationBy Arjen Karel · corewebvitals.io/state-of-cwv
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CLS shift concentration per platform

Wix sets the CLS shift concentration to a single dominant shift on 73% of its sites, and 97% of Wix sites have a good CLS, against 92% of all sites.

PlatformCLS shift concentration on its sitesGood CLS
React sites with CLS shift concentration 3,993 sitesSingle dominant shift (95%+) 59%Mostly one shift (65-94%) 22%Multiple compounding shifts (<65%) 18%92%
Wix 1,197 sitesSingle dominant shift (95%+) 73%Multiple compounding shifts (<65%) 14%Mostly one shift (65-94%) 13%97%
WordPress 1,723 sitesSingle dominant shift (95%+) 55%Mostly one shift (65-94%) 25%Multiple compounding shifts (<65%) 19%88%
Single dominant shift (95%+) Mostly one shift (65-94%) Multiple compounding shifts (<65%)
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 5,488 with phone field data · 3,993 sites with CLS shift concentrationBy Arjen Karel · corewebvitals.io/state-of-cwv
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CLS shift concentration or the platform

Does the platform explain the CLS shift concentration difference?

On WordPress, 89% of sites with a single dominant shift CLS shift concentration have a good CLS, against 83% of WordPress sites with mostly one shift. Within WordPress, sites with a single dominant shift and mostly one shift have a good CLS about equally often. On Wix, 98% of sites with a single dominant shift CLS shift concentration have a good CLS, against 90% of Wix sites with mostly one shift. Within Wix, sites with a single dominant shift have a good CLS more often.

One isolated layout jump versus cascading multi-element shifts

CLS concentration measures the ratio of the single largest layout shift to total lab CLS on pages with non-zero shift. Across 2,367 sites (59.3%) where one isolated element accounts for at least 95% of total CLS, 90% pass field CLS. When secondary shifts join in (22.4% at 65% to 94% concentration), good field CLS drops to 75%, and when shifts are spread across multiple compounding events (18.3%, 730 sites), good field CLS falls to 81%.

The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 5,488 with phone field data · 3,993 sites with CLS shift concentrationBy Arjen Karel · corewebvitals.io/state-of-cwv
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Understanding CLS shift concentration

Inspect every LayoutShift entry in your performance trace: if concentration is 95%+, fixing the single culprit container resolves CLS; if concentration is below 65%, audit header bars, web fonts, and unsized media together. Across all audited sites with lab shifts, 59.3% have a single dominant shift (90% good CLS) and 18.3% have multiple compounding shifts (81% good CLS).

Go fix it Scroll-triggered animations cause CLS → Layout shift caused by CSS transitions → Identify and fix CLS →
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 5,488 with phone field data · 3,993 sites with CLS shift concentrationBy Arjen Karel · corewebvitals.io/state-of-cwv
Related signals Largest single shift → Layout shift count → Shift direction → What shifted → By Arjen Karel · 9,570 crawled React sites (5,488 with phone Chrome field data, 3,993 sites with CLS shift concentration, October 2026) · How we measured