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Glossary

Core Web Vitals

Core Web Vitals are Google's three measures of how real visitors experience a page: loading (Largest Contentful Paint), responsiveness (Interaction to Next Paint) and visual stability (Cumulative Layout Shift).

Also called CWV.

By NightshiftDirect Research. Published . Updated .

The three measures and where good begins

Google publishes a good threshold for each measure on web.dev (web.dev: Web Vitals). Loading is good when the Largest Contentful Paint happens within 2.5 seconds of the page starting to load. Responsiveness is good when Interaction to Next Paint is 200 milliseconds or less. Visual stability is good when Cumulative Layout Shift is 0.1 or less.

Each one is judged at the 75th percentile of page loads: the value that three quarters of visits come in at or under (web.dev). So a page that feels quick to you on the office Wi-Fi can still fail for customers opening it on a phone.

What Google says they mean for Search

Google's Search documentation recommends that site owners achieve good Core Web Vitals, and says good scores line up with what its core ranking systems seek to reward (Google Search Central).

Google does not put a number on how much the scores count against everything else it weighs.

What Interaction to Next Paint adds

Loading and a steady layout are easy to picture. Responsiveness is harder to see. Interaction to Next Paint watches the interactions a visitor makes with a page, measures how long the page takes to respond to each one, and reports a single value that all, or nearly all, of them came in under (web.dev: INP).

In practice it is the gap between a tap and the page reacting: the menu button that does nothing for a moment, so the visitor taps it again. The scan measures it as E2. The usual first place to look is the heavy scripts on the page, such as a chat widget, tracking code or a page builder.

Real visitors and lab tests

Our free scan takes its real-visitor speed data from Google's Chrome UX Report when your site has enough traffic to be in it. When it does not, the scan shows a single lab test instead and labels it as one (how the scan works).

The real-visitor figure is the one the thresholds are written for. A lab test is one load at one moment. It can show you what loads slowly, and it says little about what most of your visitors see.

Where to see your own scores

Search Console has a Core Web Vitals report that shows how your pages perform (Google Search Central). If your site is not set up there yet, it is worth doing, because those are Google's own figures for your pages.

What the free scan checks

Questions

Will fixing Core Web Vitals raise my Google rankings?

Nobody can promise that, so be wary of anyone who does. Google ties good scores to what its ranking systems reward without saying how much they weigh. Fix them for the people already visiting your site, and judge the work by the before and after measurements.

Why does my small site show no Core Web Vitals data?

Because real-visitor figures need real visitors, and a new or quiet site does not have enough of them yet. Until it does, start from the lab test in your scan, and read it as a single load of your page, not a record of your visitors.

Where this fits in our work

We handle this as part of Technical SEO: The crawl, index, speed and structured data problems that keep good pages from being found, fixed and shown with evidence.

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