Core Web Vitals

What it means

Core Web Vitals are three measures of how a page feels to a visitor: how fast the main content appears, how quickly it responds to a tap, and whether content jumps under the finger.

Google uses them as one ranking signal, but what matters more is their direct link to conversion. A slow page on mobile loses visitors before they ever reach the price.

The three measures go by LCP for the main content appearing, INP for responsiveness and CLS for layout stability. They are not the score from a testing tool: a lab number is only an estimate, while the assessment rests on real visitor data from recent weeks, so gains in SEO show up with a delay.

How it works in practice

They are measured on real visitors, not in a lab. So the fixes are the ones an ordinary user feels: smaller images, fewer third-party scripts, hosting near the audience, sensible fonts.

On a landing page behind paid advertising, speed has a direct financial effect: better conversion lowers the cost per order on the same campaign budget.

When redesigning a site or moving to a new CMS, measure the values before launch and after it. A drop can then be traced to a specific change, such as a new slider or a chat window, and fixed before it shows in the number of enquiries from the site.

What to watch out for

The usual cause of poor scores is tracking and marketing scripts added one at a time without review. Each looks trivial; together they add seconds and spoil the experience on mobile as well.

Mobile and desktop are assessed separately, and so are different types of page. A company that checks only its home page on a fast office connection misses the slow pages with prices or a form, which are exactly where conversion is decided.