Glossary · Measurement and evidence
CLS
Cumulative Layout Shift, a score for how much visible content moves after it first renders, one of the Core Web Vitals. Under 0.1 is the threshold.
What CLS means
Cumulative Layout Shift, a score for how much visible content moves after it first renders, one of the Core Web Vitals. Under 0.1 is the threshold. Images without declared dimensions, late-loading fonts and injected banners are the usual causes; it is measured across the whole visit, not at load.
What CLS can and cannot support
| It can support | It cannot support |
|---|---|
| Cumulative Layout Shift, a score for how much visible content moves after it first renders, one of the Core Web Vitals. Under 0.1 is the threshold. | Images without declared dimensions, late-loading fonts and injected banners are the usual causes; it is measured across the whole visit, not at load. |
Terms this definition uses
Related terms in Measurement and evidence
The vocabulary for saying how strongly something is known.
evidence level · false positive · denominator note · percentile rank · population baseline · cohort asymmetry · self-audit invariant · unscored measurement · dated series · change receipt · regression · finding age · graded through a wall · self-audit · placeholder in record · fetcher disagreement · own-host loop · score version · row review · double-counted defect · cosmetic row · gated row · log file analysis · AI referral attribution · finding fingerprint · finding state · headroom · fix list · render gap · lab data · Lighthouse · RUM · LCP · INP · topicality · intent coverage · canary · citation rate · presence rate · answer stability
Questions about CLS
What is CLS?
Cumulative Layout Shift, a score for how much visible content moves after it first renders, one of the Core Web Vitals. Under 0.1 is the threshold.
What does CLS not show or guarantee?
Images without declared dimensions, late-loading fonts and injected banners are the usual causes; it is measured across the whole visit, not at load.
Which area of the glossary does CLS belong to?
Measurement and evidence: The vocabulary for saying how strongly something is known.
See it in the full glossary · 668 terms across 19 areas.