Cumulative Layout Shift (CLS) quantifies how much elements within the viewport move around during page load. CLS helps pinpoint how often unexpected movement occurs on your pages.
The Cumulative Layout Shift score is the sum of scores from all of the unstable elements that move around during page load. CLS is under active development and the exact formula might change, but currently, the layout shift score is a product of:
Learn more in Cumulative Layout Shift: Measure and Avoid Visual Instability and in Milica Mihajlija’s post, The New Generation of Performance Metrics for Better User Experience.
| Good CLS Measurement | Poor CLS Measurement |
|---|---|
| ≤ 0.1 | > 0.25 |