What is a good CLS score?
- Good: 0.1 or less
- Needs improvement: between 0.1 and 0.25
- Poor: above 0.25
Google looks at the 75th percentile of real visits, so at least three in four visits should score 0.1 or less.
Common causes
- Images, videos and iframes without a width and height
- Ads, embeds and banners that load late and push content down
- Web fonts that swap in and change the size of the text
- Content inserted above what is already on screen, such as notices
How to fix CLS
- Always set a width and height, or an aspect ratio, on images and video.
- Reserve space for ads and embeds before they load.
- Preload key fonts and use fallback fonts of a similar size.
- Show banners and notices as overlays, or reserve their space.
Measure CLS with PageSpeed Insights and the Core Web Vitals report in Google Search Console.
CLS example
A reader opens an article and starts reading the second paragraph. An ad loads above it and pushes the text down by 250 pixels. The reader loses their place and taps the wrong link. The page scores a high CLS. The site fixes it by reserving a fixed-size space for the ad, so the text stays put when the ad appears.
How to find and fix layout shifts
- Open PageSpeed Insights or the Core Web Vitals report in Search Console to see the CLS of real visits.
- Use Chrome DevTools (Performance panel, Layout Shift track) to see which elements move.
- Set width and height, or an aspect ratio, on images, videos and embeds.
- Reserve space for ads, banners and cookie notices.
- Preload important fonts and use a similar fallback font to reduce text jumping.
- Re-test after the change, then wait for field data to update, which takes weeks.
CLS mistakes
- Inserting banners or notices above content after the page has loaded.
- Lazy-loading images with no space reserved.
- Testing only on a fast desktop. CLS is often worse on phones.
CLS FAQs
Is CLS a ranking factor?
It is one of the Core Web Vitals, which are part of Google’s page experience signals. Good content still matters more. See page speed.
What else is in Core Web Vitals?
Largest Contentful Paint and Interaction to Next Paint. Read about user experience and mobile page optimization.