The State of Web Vitals

Layout shift causes (CLS attribution) and Cumulative Layout Shift

Element box growth (78.5%), sibling displacement (34.7%), web font reflow (23.9%), unsized media (3.9%), and late embed growth (0.5%) across 134,853 sites with recorded layout shifts.

Field data PhoneDesktopAll Scope All sites October 2026 edition · Phone field outcomes

23.9% of sites use web font reflow layout shift causes, and 87% of those sites have a good CLS, against 89% of all sites.

The State of Web Vitals · October 2026 · 210,902 crawled sites · 126,761 with phone field data · 134,853 sites with layout shift causesBy Arjen Karel · corewebvitals.io/state-of-cwv
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CLS pass rate

Sites with web font reflow layout shift causes have a good CLS most often: 87%, against 89% of all sites. Sites with late embed growth shift causes have it least often, at 60%.

SitesGood, needs improvement, poor CLSMedian
All sites126,76189%0.00
Web font swap text reflow 23.9%20,07287%0.00
Unsized media expansion 3.9%3,43786%0.00
Element box growth (box_grow) 78.5%66,85885%0.00
Displaced sibling element 34.7%29,33484%0.00
Late iframe / embed growth 0.5%50260%0.06
GoodNeeds improvementPoorSites: with Chrome field data
The State of Web Vitals · October 2026 · 210,902 crawled sites · 126,761 with phone field data · 134,853 sites with layout shift causesBy Arjen Karel · corewebvitals.io/state-of-cwv
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Layout shift causes usage

Element box growth is the most used: 78.5% of sites. Web font reflow is 23.9% of sites.

Sites using each option (sites can use more than one) 134,853 sites
Element box growth (box_grow) 78.5% Displaced sibling element 34.7% Web font swap text reflow 23.9%
Element box growth (box_grow) 78.5% Displaced sibling element 34.7% Web font swap text reflow 23.9% Unsized media expansion 3.9% Late iframe / embed growth 0.5%
The State of Web Vitals · October 2026 · 210,902 crawled sites · 126,761 with phone field data · 134,853 sites with layout shift causesBy Arjen Karel · corewebvitals.io/state-of-cwv
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Understanding layout shift causes

How different DOM mutations translate into field CLS failures

Not all lab layout shifts hurt real users equally. Sites whose shifts come from web font swaps (23.9%) pass field CLS 87% of the time because line-height adjustments are small. Element box growth (78.5%, 85% good CLS) and displaced siblings (34.7%, 84% good CLS) cause moderate drops, while late iframe and embed growth (0.5%) pulls field CLS down to 60% (median CLS 0.06).

Eliminate late embed and banner growth first by reserving min-height containers for ad slots, promo bars, and third-party widgets. While 78.5% of shifting sites see element box growth (85% good CLS) and 23.9% see font swap reflow (87% good CLS), sites with unreserved iframe or embed growth (0.5%) pass field CLS only 60% of the time.

Go fix it Identify and fix CLS → CLS from images and media → Fix layout shift from auto-sizing images → Keep text visible during font load →
The State of Web Vitals · October 2026 · 210,902 crawled sites · 126,761 with phone field data · 134,853 sites with layout shift causesBy Arjen Karel · corewebvitals.io/state-of-cwv
Platform & Framework Takeaways

How layout shift causes plays out per platform

What the field data shows when you isolate a single CMS or framework.

WordPress 46,441 sites
89% vs 51% good CLS (font swap vs embed growth)

On WordPress sites with lab layout shifts, embed_grow sites pass field CLS at 51% vs 89% on font_text sites.

Across 46,441 WordPress sites with lab layout shifts, 78.5% record element box growth (87% good field CLS), 24.2% record web font reflow (89% good CLS), and 0.7% record embed_grow (51% good CLS).

Read the WordPress CLS attribution breakdown →
Shopify 5,582 stores
79.8% box growth (91% good field CLS)

Among shifting Shopify stores, 79.8% record box growth (91% good CLS) and 35.8% record sibling displacement.

Across 5,582 Shopify storefronts with lab layout shifts, 79.8% record element box growth (91% good field CLS) and 35.8% record sibling displacement (90% good CLS).

Read the Shopify CLS attribution breakdown →
Related signals Layout shift count → Shift direction → Largest single shift → Shift concentration → By Arjen Karel · 210,902 crawled sites (126,761 with phone Chrome field data, 134,853 sites with layout shift causes, October 2026) · How we measured