CLS shift concentration and the Core Web Vitals
Among sites recording lab layout shifts, 56.3% (75,920) concentrate 95% or more of their CLS into a single shift (90% good field CLS), while 19.4% suffer multiple compounding shifts (82% good field CLS).
56.3% of sites use a single dominant shift CLS shift concentration, and 90% of those sites have a good CLS, against 89% of all sites.
CLS pass rate
Sites with a single dominant shift CLS shift concentration have a good CLS most often: 90%, against 89% of all sites. Sites with multiple compounding shifts shift concentration have it least often, at 82%.
CLS shift concentration usage
A single dominant shift is the most used: 56.3% of sites.
Understanding CLS shift concentration
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 75,920 sites (56.3%) where one isolated element accounts for at least 95% of total CLS, 90% pass field CLS. When secondary shifts join in (24.3% at 65% to 94% concentration), good field CLS drops to 84%, and when shifts are spread across multiple compounding events (19.4%, 26,114 sites), good field CLS falls to 82%.
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, 56.3% have a single dominant shift (90% good CLS) and 19.4% have multiple compounding shifts (82% good CLS).
How CLS shift concentration plays out per platform
What the field data shows when you isolate a single CMS or framework.
WordPress 46,441 sites WordPress pages with multi-shift lab CLS (18.1%) pass field CLS at 84% vs 91% for a single shift.
Across 46,441 WordPress sites with non-zero lab CLS, 57.8% have 95%+ of their CLS in a single shift (91% good field CLS), 24.0% sit at 65% to 94% (87%), and 18.1% have multiple shifts (84% good CLS).
Shopify 5,582 stores 57.5% of shifting Shopify stores have 95%+ of their lab CLS in one shift (94% good CLS vs 90% multi-shift).
Across 5,582 Shopify storefronts with lab layout shifts, 57.5% have a single dominant shift (94% good field CLS), 23.7% sit at 65% to 94% (90%), and 18.8% have multiple shifts (90% good CLS).
React & Next.js 3,993 sites React & Next.js sites with multi-shift lab CLS (18.3%) pass field CLS at 81% vs 90% for a single shift.
Across 3,993 React sites with lab layout shifts, 59.3% have one isolated shift (90% good field CLS), 22.4% sit at 65% to 94% (75%), and 18.3% have multiple shifts (81% good CLS).
By Arjen Karel · 210,902 crawled sites (126,761 with phone Chrome field data, 134,853 sites with CLS shift concentration, October 2026). How we measured.