Cumulative Layout Shift (CLS)

Cumulative Layout Shift (CLS) is the Core Web Vital that measures the visual stability of your page. The score maps how many elements shift unexpectedly while the page loads, so how calm or how jumpy your layout feels.

What causes layout shift?

You know that irritating moment: you want to tap a button and suddenly the whole page slides down because an image or ad loads in. That is a layout shift. CLS adds all these unexpected shifts together into one score. Google considers a CLS below 0.1 as good, between 0.1 and 0.25 as fair, and above that as poor. Unlike LCP, which is about load speed, CLS is purely about stability: nothing should slide away under your fingers.

How do you keep your layout stable?

The most common cause is media without fixed dimensions. Always give images and videos a set width and height, so the browser reserves the space in advance. The same goes for fonts that load late and cause the text to reflow, and for banners or lazy-loading blocks that appear suddenly. Also reserve space for dynamic content that arrives later. This way your page stays where the visitor expects it. CLS forms the Core Web Vitals trio together with LCP and INP.

Why this matters for your growth

At Customer Impact we look at what produces customers, and a jumpy page costs trust. A B2B decision-maker who accidentally clicks the wrong element or loses their place drops off before reaching your form. A stable layout is not a cosmetic detail but part of a page speed experience that protects conversions.