Cumulative Layout Shift (CLS)

Cumulative Layout Shift (CLS) is one of Google’s Core Web Vitals metrics that measures the visual stability of a webpage as it loads. A poor CLS score occurs when elements, such as images without defined dimensions, dynamic ads, or asynchronously loaded widgets-suddenly shift the layout, causing the user to lose their place or accidentally click the wrong button. Google algorithmically penalizes pages with high CLS scores because they create a frustrating, frictionless user experience. Achieving a passing CLS score requires strict technical implementation, such as explicitly defining width and height attributes for all media assets and reserving space for dynamically injected content.

Cumulative Layout Shift (CLS) Simplified

Cumulative Layout Shift is Google’s way of measuring if your website jumps around while someone is trying to read it. If a user goes to click a link, but an image suddenly loads and pushes the link down so they click an ad instead, Google will lower your rankings.